Changing が to の outside of relative clauses

Question

A girl asks her mother why she can't keep a catalogue and is told:

「明日の午後に私もお歳暮を買いに行くから、それの参考にするのっ。」
I'm going to buy the year end presents tomorrow afternoon, so I'll use that (catalogue) as a reference.

How should I parse the part in bold? Why is it not それが参考にするの

I'm familiar with the idea of replacing が with の in relative clauses to move the emphasis away from the thing marked by が. But, the only way I can make a relative clause is if the の at the end of the sentence is something other than the explanatory の, which seems unlikely. What am I failing to understand?

Answer 1

I think Aは(が)Bを参考にする is translated as A consult(refer to) B like 私はこの本を参考にした( I referred to this book).

I think AはCをBの参考にする is translated as "A refer to C for B" like 私は、この絵を、私の絵の参考にする( I refer to this picture for my picture).