Amongst the "duplicate data" are there any fields whose value can link the data in one form from database A with the matching record in database B?

Do any of the 20 or so have values that could be used to join the two records into one? In other words, can they act as a "key" value?

Is the value in any of those elements the same in both the records in question and definitely unique in that no other records but those two will have that value in that element?

The simplest thing you can do is merge the two databases/forms into a single application. Then edit the larger existing form, adding the additional elements from the smaller form (should be about 100). Reorganize and relabel the elements already on that form as needed. To make additional room, click on the form's surface and press the Shift-Arrow keys. You can use the rubberband select to move larger groups of elements out of the way.

Once you have your enlarged form built, I would recommend using a @XLookupSourceList in a Mass Update (using the value of a shared element with a shared unique value as the key), and the String Array commands to populate the additional elements from the smaller form. Once that is complete (and very verified), you can trim the database for the smaller form out of the application.

A more complicated solution, though it is less manual labor, is to make the smaller form a relational subform of the larger form that is not allowed to advance (using NotifyForm). This will effectively make it a "part" of the main form because it can only save the first record and cannot advance to the second record. This is not a very elegant solution - though it is a lot less work. I haven't tried to built an app that works this way, so the advice is untested.

If you do decide to go the second route, you should do an ASCII export of the result and then clear the application of user data, set subform to be naturally linked and read the ASCII data back in. That way you will not take a speed hit for being relational when you don't really need to be.

In any case, you will need to remove the "shared" elements from the resultant form, so that your form does not have duplicate elements and to reduce general confusion.

You're welcome. Let us know how it goes or if there any specifics we can assist you with.