Automations w/linked records: can only do one at a time

I’m running a school and trying to automatically generate a sheet that shows which students will be in attendance on which days. We have several part-time options, for example, someone can come Mon-Tues, others may come Wed-Friday, some Mondays only…
For reason that seem unnecessary to explain here, I’m using Jotform to collect initial info, so I’ve created an automation that searches the field Jotform populates (Days attending. Looks like “M; T”, etc.) for “M”, and the action it takes is to select “M” from the linked field of days attending.
It worked great. Then I created one for Tuesday. It also worked great. Except that if someone is attending Monday AND Tuesday, one will cancel out the other. How do I get it to put in BOTH?

I’ve literally been working on this for HOURS.
@Elias_Gomez_sainz @Mohamed_Swellam @ [ScottWorld]

You have to put a comma in between the values, and send all of the values together into the linked record field.

I understand that if I’m doing one automation, but it seems like each automation overwrites the last one.

You only need one automation action to do this. Just create a formula field that substitutes your semicolons for commas, and insert that formula into your linked record field.

However, if you really want to break it up into extra automation actions, then you need to insert the existing field first, followed by a comma, and then add the new value after the comma.

That’s what I’m thinking, but I can’t figure out what to put in the Update Record step to retain the existing inputs. I believe I need multiple inputs, because I need to only add linked value “M” to records that include “Monday”, and only add “T” to records that include “Tuesday.”