If it´s not for a training position, it is quite easy.
The two best ones start and the third one is backup for both. That will give you around 40 minutes for the starters and around 16 minutes for the backup.
A C
B C
If you want to have a management on minutes to ensure a decent game shape, you will need a fourth player for the second match. Then you can play like that:
A C
B D.
I have a massage doc, and I have experienced no major problems with around 75 weekly minutes, which you will get with that option.
You can play C and D in the scrimmage to fill the minutes.
A, B and C: ~75 minutes.
D: ~60 minutes.