Linking several records to a single record in another table

When you're linking the records, are you spreading the existing contents of the linked record field in record B, or are you overwriting with every new addition? If you don't make sure to re-add the existing linked records, you'll lose them whenever you overwrite to add a new one.

I figured out how to use the checkbox method I stated above, and I just added all of the records without a for loop. I still want to automate the process, so you do not have to click the check box and it does it automatically. For the automation I didn't figure out, I did remeber to re-add the existing linked records, however, when I run it, it is inconsistent in which values it appends to the singular record I am trying to link to. (though when I test it in the automation editor it works for individual records).

can you ss the step you've built in the editor? And possibly the automation can check the boxes for you to handle the additions?

This is what I  have right now. A record in the estimating summary is where I am trying to append linked records from the BOM. So what I do (In the loop), is 1) I create a record for BOM, 2) find the corresponding record in the Estimating summary, 3) and attempt to append every record from the BOM to the corresponding record in Estimating Summary. The steps before work perfectly, it is simply the last "Update record" step that does not work.

However, this does not work, and on a trial, it returns what I attached in the screenshot below. What I got was incorrect as I have 100 records that I loop through in the automation above. So theoretically, I would be getting 100 records attached to that one cell in my Estimating Summary.

Furthermore, it is not consistent in what it returns as a second and thrid trial produces the cells shown down below. However, it is usually consistent in returning only 4 records, though always different.

A potential reason to why this is occuring is that the automation is iterating too fast, and therefore returning only linked record in its current step: however, I think that is not the issue.

Again, I have the solution I stated above that requires one to check a box, which populates the cell with the designated BOM records. This method selects all of the records and then updates the cell all in one automation (without loops). The only way I can think of an automation checking the box is adding an "update record" step after all the records are created (but i cannot put one after the loop). I also thought of updating the cell after every time with ALL created records in the BOM. However, this makes the process unreasonably slow, especially as I have 150+ records that have to be appended to the cell.

Have you changed the ordering of the addition? Like putting the record id after the list? Zapier requires you to put it first when adding to spread contents, but maybe doing the opposite in AT would work. Flooding the loop could be possible but I would expect AT to be better about batching for you.

You'll also run into issues when you get over the hundred record mark as a find record step can only return 100 records at a time. Do you have a zapier account? This task would likely be more easily accomplished there, and you could use a delay after queue to ensure you're not flooding.

When I try putting the record id after the list, it does not append any of the records to the cell I want them linked to. (The cell remains empty)

As for the limitation of 100 records, I split this automation into two as I do not have more than 200 records that I deal with, so the limit is probably not the issue. 

Regarding Zapier, I have an account; however, I do not have the pro plan so I am limited to only 1000 zaps. This means that I do not have many test runs and I rather not pay for an extra service. When I ran the test once it did work (In zapier), but it missed linking a few records (for some reason). This time I just ran my logic after a record was created (in the BOM). But when I put the same exact logic into airtable automation, it completely breaks (similar result to what I got before). Logic is down below. For this logic, I also attempted switching the record ID and the List in the field category: however, this also did not work.

My assumption is that records are being created too fast so when it checks for the previos "List of IDs", that list is not updated which in turn breaks the automation. I am just wondering, is there a way to check when all your records are done creating? If this is possible, I will be able to implement a method that works.

To force sequential ordering I'd use a scripting step rather than the built in 'find records' and 'update records' honestly. You can work around the 'find record' limit that way, and a javascript loop will always iterate sequentially, so no need to worry about flooding. You can also only use one write step that way, rather than 100+ which can be very CPU-intensive. Just loop to create the full record list, then update once at the end. 

I am currently using the free trial version of the Pro plan so that is not accessible to me currently.

You should be able to on a pro plan, is the base you're working in located in the workspace with the pro plan, or is it in your personal workspace? Anda re you adding a scripting step, or trying to add a custom extension?

I currently only have the free "PRO trial" so I do not think I have access to it. The base is under a workspace with the pro trial and I am trying to add a scripting step. Custom extensions work for me and I am able to link a button to activate it.

The custom extension will be great! Just a bit of a steeper learning curve if you're not familiar with javascript. Be careful as you will lose it once the trial is over if you don't upgrade permanently. 

How do I connect the extension to an automation? I already have scripts that I run on activation as well as scripts that are activated with a button, but I am unsure how to connect it with an automation or have it mimic the same behavior.

Extensions aren't meant to interact with automations. You can set the extension to run with a variety of triggers though. Guessing you already found it, but this link will give you an overview of the available input types.

Are the avaliable input types for when the script already begins running (awaits input from user) or is it to activate the script (before it is ran)? Correct me if I am wrong, but I am trying to run it without having to even run the script but the input types are not triggers to run the script. 

The run a script action that the above image recommends is the "run a script" step in automations which is outside of my plan's scope.