Visual studio 2015 debugging multiple solutions

Question

Hi,
I have two solutions lets say SolutionA and SolutionB. Here SolutionB has class library which is referred in SolutionA. Now I want to step-in through the SolutionB from SolutionA while debugging it.

Please assist.

Many Thanks

What I have tried:

I tried this, sort of working but not completely.
a) opened both solutions in separate VS2015 instances with break points in it.
b) Unchecked "Enable Just my code".
Ran solution A and hit the breakpoint in SolutionA then I did F11 for Step-in to SolutionB. It was stepped-in but respective file (Which is in SolutionB) opened in same VS2015 instance where SolutionA is running.

I want debugger should jump on to SolutionB VS2015 instance.

I tried even attach to process, It was doing same along with SolutionB VS2015 instance went into some weird blocking state (there were four icons on top. Go to live visual tree,Enable selection, Display layout adorners, track focused element)