I have two tables (contact and group) with at least two fields in each: group and sub-group.

I would simply like to press on the down button on a layout on the group and sub-group fields connected to my contact table to select the group and sub-group data from the Group table.

Not sure i need a relationship betweeen the two tables but if I did, I am not sure what fields to tie them together with.

NOTE: Group and sub-group data always is entered in the Group table since it is the source. All other tables would retrieve data from this table.

thanks in advance.

You won't need a relationship.

When you choose "Drop-down List" for the next option (Display values From:) choose "Define value List"

Create a new list titled "Group" (or whatever you would like it to be)

Select: Use values from field

Click on Specify Field

Choose the correct table and the correct field and make sure the bottom says "Include all values" and that should do it!

I hope this solves your problem :P