I haven’t taken AFM yet, but I have taken SBL and APM, and there is definitely some overlap in content between the SBL and APM exams. Perhaps consider doing AFM in Sep, and then attempt the other two in Dec?
Certainly possible and advisable. My friend took both SBL and AFM in the June sitting and passed both comfortably today 🙂
I personally like doing one numbers and one writing paper at the same time as it gives you something different to do versus doing APM and SBL (which are both big writing papers).
Just be warned with AFM that it’s very numbers based and a lot of students who aren’t comfortable with that may struggle but to answer your question, yes doing SBL with AFM is a good idea if you like both 🙂