Forms :: Creating Group Membership Database

I am having problems developing a membership database - I have three main tables.

1. A table of 600 members of an organisation

2. A table of the subgroups these members may join, about 80 in total.

3. A table of the members of each group.

The members do not have a unique ID - complicated reason for this so I use a system assigned ID. Group ID does have a unique Id but I chose to use a system assigned ID.

Table 3 records effectively consists of just two fields, memberID and groupID. When I create a form and subform to enter these values all is well. But I cannot expect users to know these values, so I have been trying to create a subform that creates/lists/removes members from groups, using a Group main form with a member tabular subform with a surname search through a combobox. Groups have between 5 and 20 members.

e.g enter 'smit' in the combobox on the subform and a list of smiths is displayed together with the full name, from which the user selects the correct entry. At this point the record showing for instance, Paul Smith belongs to Group 17 is written to table 3. All sorts of issues arise, too many to document.