I have a Workbook with two worksheets – People and Memberships

Column A of People contains the person’s unique ID number.
Column A of Membership contains the unique Membership ID number, and column B of Memberships contains a person ID number, which refers back to Column A of People. There can be more than one Membership per Person.

I want to have a formula, or VBA code, that will insert into a new column in People a comma separated list of all that person’s Memberships.

If there was only one Membership per Person I could easily use a VLOOKUP but because there are many Memberships per Person I don’t know how a VLOOKUP would help. And specifically I need the result to be in a single column using commas to separate the IDs.

Really grateful for any help here! Thanks