git - Merging master branch into feature branch then back again -

I have a feature branch that was split into branches from my Master branch some time ago. Since then, Facilities have been developed, which have now been merged with all the master branches. Now I need to merge the master branch to this old facility branch (to get some important code updates from the master branch) Can I do this and then, when I have completed the test on this old facility branch, Merged it back into the master branch (to live first)?

Yes.

There is little / no danger in the conflict, and the branch code has been tested in the Master with the latest changes.