Forms :: Check Boxes To Enter And Delete Records?

I have a form to enter archaeological features in a feature table. Each feature is present in one or more archaeological strata, for which I have a stratum table. There are 41 strata in total named 1A, 1B, 2A etc. On the form I want a checkbox for each of these and then to make it add a record to the stratum table for each of the selected strata. The stratum table and feature table are connected by the feature_primary_ID (key in feature table), so when making a new record I need this primary ID and the respective strata to be entered in the fields.

At the moment I've got something like this:

Code:
Private Sub Check1_Click()
If Check1.Value = True Then
DoCmd.RunSQL "INSERT INTO tbl_FEAT_STRAT (feature_primary_ID, stratum_ID) VALUES ((feature_primary_ID of present record),Label2.Caption)"
Else
DoCmd.RunSQL "DELETE FROM tbl_FEAT_STRAT WHERE feature_primary_ID = (feature_primary_ID of present record)"
End If
End Sub

For starters, I dont know how to get the feature_primary_ID from the features table (also represented in the form as a field) and use it to make a new record in the strata table.

Second, when using this code I need a copy for each of the 41 strata checkboxes. Creating lots of redundant code. Easier would be a generic code that loops through all the checkboxes after they've been checked and then add new records for each of the checked boxes. Tried something with a command button, but couldn't get it to work.