can this be even done, and if yes then what is the safest way to do so?
It can be done... Start reading here:
https://docs.oracle.com/cd/E36784_01/html/E36801/grubadmin-1.html\#scrolltoc
Sure, I routinely have many Linux distributions, Windows and several Solaris boot environments in a multi-boot configuration.
The safest way is to have Linux install its boot loader on a dedicated, non Solaris partition or its own
root partition and chainload the Linux boot loader(s) from Solaris Grub.
Or run both under a hypervisor, e.g. VMWare. Than you can run them at the same time if you have enough memory..