SG actions rule clarification

Here's a SG Question for Jon.

A squad has eight troopers, 6 riflemen with advanced assualt rifles 
Fire-power 3, and two SAW's Fire-power D8. This Squad can lay out a 
fair bit of fire power in just one action but can this unit also divide 
their combat between 2 actions ie. 
1st Action: 3 riflemen and 1 SAW, 
2nd Action the other 3 riflemen, the other SAW. 
Or must all of the riflemen who are going to fire, fire in the same 
action with only the two SAW's being able to fire in the other action 
because they are support weapons.

Trevor Dow 
Adventurous Spirit, 
Torquay, Australia.