Hi @cliffcoulter.
The MKR2UNO adapter is really not suitable for your intended application.
This product is intended to allow you to connect an Arduino MKR Board to Arduino shields that were made for the Arduino Uno board's form factor.
This graphic demonstrates its usage:
You would have to replace the headers on the MKR2UNO just to connect it to the MKR2UNO adapter. If you are going to do all that work, you would be better to instead use a "proto shield" (like this) to connect the MKR Shield to the Uno.