Hi,
Looking for some help to check if the approach I'm using is ok and some help with the implementation would also be appreciated.
On a screen of my app, the form references items from 1 SharePoint list called Test Requests.
An admin uses this screen to assign requests to someone of the team. Depending on the requested test, a certain amount of numbers need to be assigned to a request. I use a combobox to present these to the admin:

These T-Numbers come from a different SharePoint list:

The admin can select a certain amount of nrs to link to the request.
These I display in a Gallery, for "user friendliness", they can easily remove certain nrs from there as well, easier then via the combobox:

What I'm struggling with is to Patch/Update the selected nrs in their SP list and set their status to "Reserved". It always results in new identical numbers being added to the list.
I try to achieve this via a "Reserve" button:

This is the full content of my DataCard:

All help, really appreciated!