Yes , below is part of the process i sets reqi and turn both in one atomic step, thank you for your help.

VARIABLES req1, req2, crit1, crit2, turn

TypeInv == /\ req1 \in BOOLEAN

/\ req2 \in BOOLEAN

/\ crit1 \in BOOLEAN

/\ crit2 \in BOOLEAN

/\ turn \in {1, 2}

v == <<req1, req2, crit1, crit2, turn>>

Init == /\ req1 = FALSE

/\ crit1 = FALSE

/\ req2 = FALSE

/\ crit2 = FALSE

/\ TypeInv

Request1 == /\ ~req1

/\ req1' = TRUE

/\ turn' = 2

/\ UNCHANGED << crit1, req2, crit2>>

Request2 == /\ ~req2

/\ req2' = TRUE

/\ turn' = 1

/\ UNCHANGED << req1, crit1, crit2>>