I beleive that she was contacting me to try and use me to get my step-son back together with her again.
However you have stated that she could have other motives which sounds concerning. What could they be ? Also the thought of red flags also raises an alarm.
A disordered person can triangulate in all sorts of twisted ways. I have a sibling that has come up with all sorts of twisted stuff over the years, none of which is based on reality. She could be talking to you about the most innocent stuff and tell other people a completely different story. The only true part is "I talk to <fill in the blank> all the time." If somebody were to ask you if you talk to her, you will likely be honest and say "yes" without knowing the whole story.
If she was wanting somebody to help convince your step son get back with her, why isn't she contacting his mom? I would think a mom would have more sway than a step dad.