Sequential numbering - not autonumber

[EMSR]

I've seen variations of this question, but can't seem to find the best solution for my use case. (FYI - I'm on the Free version) 

I need to create sequential numbers based on a linked record. 

Example: 

Our "Jobs" table has all our jobs and their corresponding data. At times, certain jobs require a change order.  The format we use for this is the 544-01, 544-02, 652-32, 652-33, and so forth. The first number specifying the previously assigned Job# and the second being the change order #. 

When using autonumber the numbers aren't sequential if a record in between isn't specified by a single select as a Change Order. Making our records seem scattered and really confusing the customer when they received change order 15 and the next one change order 18. 

Any suggestions? 

[Sho]

@kuovonne Guide will be helpful

Sequential Numbering of Records · Kuovonne's Guide to Airtable (coda.io)

[EMSR]

Thank you for this, as it may be helpful in the future, but the only option that may work would be the checkbox automation. We already use a lot of automations making it hard not to cap out automations on the free plan, the checkbox option would push us over quickly.