In a query, you can get every record associated with the values in a multi value field by adding the .Value property in the query:
https://support.office.com/en-us/art...3-b6624e1e323a
You should be able to use that query as a table in an append query to append each record to some other table. Why you'd want to append to a table that by your description is not related to the other table is a mystery.
To avoid human errors during the input process, we would like this field to be a selection drop down,
This reads like you're working in tables, which you should not be doing. Stop doing that and the multi value problem goes away.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.