Wildcard options for PX Product Mapper URL rules

This is closely related to this conversation, but one key part of it wasn’t addressed or implemented, as far as I can tell...

I have a landing URL that users visit:

1. /function/{{unique identifier for a project}}

We also have pages off of that main page:

2. /function/{{unique identifier for a project}}/sub-function1
3. /function/{{unique identifier for a project}}/sub-functionN

Since it’s really important to track users visiting the landing URL, how do we wildcard A so that it doesn’t also capture B and C with every instance?