QUO means "whither, where (to)", and DEHINC means "hence, from here".

But the English "for our lawyers" can mean "on behalf of..." ("shopping an anniversary present for my house-bound father", i.e., I am his agent), or it can mean "with regard to, for the benefit of..." ("shopping a birthday present for my father", i.e., I am ).

You must use the Latin PRO if the expression means, "Whither from here (do we go) on behalf of our lawyers?/What does one do now for the lawyers' services?"

But you must omit it if the sentence means, "Whither from here (will things go) for our lawyers?/What must the lawyers now do?"