Restore dual boot after Windows installation + xfs issue

Dear All,

good morning.
I have RHEL 7 installed on my Dell Workstation.
In this workstation I have 4 hard disks and 4 /home directories (/home1, /home2, /home3 and /home4).

I need to install Windows 7 for research requirements and I would like to shrink the /home4 partition and use part of the fourth hard disk
I plan to use GParted, even though I am having issues in shrinking the xfs partition.

First question: is there any special operation that I have to do to shrink an xfs partition without deleting it?

Second: when I have Windows installed, I will not be able to access RHEL anymore. Do You have some suggestions to
restore the dual boot? I use the GRUB2 boot loader.

Thanks in advance and my best regards

Giacomo