Help configuring call pick up line

I’m struggling to find a way to program the following scenario:

An inbound route currently to a call flow control, which directs the call to one of two ring groups. This part works fine.

There are some users not in either ring group that would like to be able to pick up calls if they hear them ringing all phones but no one is in the office. The pickup code would pickup from the ring group. This used to work, but since we implemented the call flow control, we need to be able to pick up from either ring group at any time, while still only using one button.

I’m wondering if anyone has an idea on how to best deal with this?