Hi,
if you want to add a second schedule for exisiting backup job, of course you can do that.
You just add the second schedule and change the protection for it.
In the schedule file (instead of using the GUI) you could have something like the example below:
-incr 1 -protection -weeks 2 -every -day Mon Tue Wed Thu -at 17:00 -full -protection -weeks 54 -every -day Fri -at 17:00
Best regards
Daniel