Do I insert a Find & Constrain found set AFTER the GTRR command?
Are the Addresses in a separate table or in the same Contacts table?
You can use * to find a field that has some data in it (is not empty).
With the relationship linking connections to contacts, you can use that relationship to specify an * in the address field of the related contacts table as part of your find criteria. Then your find can be by user ID but omit any that have an empty address field. This eliminates the need to use a calculation field.
And if you get slow performance, you can find all by ID, then constrain by the * in the contacts::Address field to speed up the find as has already been suggested.