Advice on fb flex and booty simultaneously

I think that when I complete fb strong I'd like to start fb flex and fb booty, since I love strength training and I want to have 5 days on and 2 rest days, has anyone else done this? And if so how'd you put them together did you do lower body 3 of the days and upper twice and then vice versa the following week or double up on a day since you were targeting different muscle groups? Thanks in advance!