i think the choice of TRX MAIO depends on the nature of your malist
if the frequencies of the malist are consecutive, the MAIO should have a difference of 2 to avoid adjacent interferences. so the allocation should be
s1 trx1 = 0
s2 trx1 = 2
s3 trx1 = 4
s1 trx2 = 6
s2 trx2 = 8
s3 trx2 = 10
s1 trx3 = 12
s2 trx3 = 14
s3 trx3 = 16
also remember that your MAIO should not go above N-1 (N: number of frequencies in the MALIST)