Need to do a calculation based on a "last name" based on the result of the "first name"

What I want to be able to do is search for a query where all the first names are the same and populate all those with the same formula.
So in the example sheet I made, I'd like to be able to populate all the "False" cells with the result from the query search "clare". I figured the best way to do this would be "where first name is "equal" calculate result for ="clare".

Let me know if this makes sense. I may just upload exactly what I want done.

You have 2 "Clare" entries.
Which Clare result did you want to use to replace the "false"

A Index/match will do the first "Clare" result but what you are asking doesn't make sense.

In the next column it would help if you entered what qty SHOULD populate if it wasn't "false".