First up, the SNAP-AIMA-8 module.
The thing to keep in mind with this module and some of our other modules is isolation.
Can your transmitters work with their neutrals tied together?
This snip is from the SNAP Analog Input Module Doc - #1056
As you can see from the diagram, it clearly states that the even terminals are all tied together.
So, check out your three pressure transmitters, there should be some information in their manuals or use guides.
Some of the answer might come from if they are self powered, or if they need a loop power supply.
If you do need isolation, the look at the SNAP-AIMA-i module.
When it comes to the SNAP-AILC, the answer there depends on how many wire your load cell has.
If it is two or three wire, then you can connect two into one module.
If it is 4 wire, then as you can see, you are going to need a module per load cell for that.
This snip is from the SNAP-AILC manual - #1590.
Hope that is of use.