The safest general-purpose way for multiple questions is

{ IF "{ granteemf \*Upper }" = "F" "{ IF "{ grannteesp \*Upper }" = "S"
"both F and S" "M or P" }" "M or P" }

But you could also consider something like

{ IF "{ granteemf \*Upper }&{ grannteesp \*Upper }" = "F&S" "both F and S"
"M or P" }

(You need something in the middle of the two results because

{ IF "{ granteemf \*Upper }{ grannteesp \*Upper }" = "FS" "both F and S" "M
or P" }

would result in "both F and S" if the user responded FS to either the M/F
question or the S/P question and left the other one blank)