[Scip] Behavior of scipFixVar

[sct]

Hi,

I have some questions about the behavior of scipFixVar.

After solving a problem for some iteration, I stopped it & find that 
some variables are definitely 0. I wish to continue solving a smaller 
problem rather than the original.

a) Do I use scipFixVar on the stopped problem? Or
b) I create a new copy of the problem from the onset & use scipFixVar on 
the new copy. With this presolve, will remove the known variable & as a 
result the problem will be smaller.

If I do b), subsequent solving may find some solutions found before 
during the first solving. Can this be avoided by loading (into the new 
copy) solutions found before? What scip command can I use to load these 
solutions?

Thanks a lot.