Now the Question of updating data on the table. Here there is something not clear to me from what you have stated above. If you are trying to update only certain records of the table while leaving others, which were updated last time untouched, then you have to device a method to identify records for updating into the table and to leave others untouched.

For example: You can introduce a Date field in the Access Table and update this field with the current date while updating data from excel table. Next time you can setup criteria to exclude these records based on the last update date and update others etc.

In either case it is better to create a Make-Table Query, to create a copy of the Access Table (Backup), and add it to the Macro before the update Query line. So that if you find that something went wrong then you can restore the data from this copy of the Table.

You may create Queries on Linked Excel Table and on Access Table on UniqueIDs (as you have stated) and link them in a common query on UniqueID and check the output records or count of records through VBA (=DCount("*","QueryName") to check whether any matching records are there in both tables which likely to overwrite the earlier updated values before actually running the update Query.

Regards,
a.p.r. pillai