Yes, you can combine any esters of test in the same cycle. The key is to make sure you are still gettting the same amount of gear per wk and not swithing to a lower weekly dose. Personally, I've found that I seem to respond better when i make regular changes to the gear I'm using. I switch esters of test every 8 wks. I would start with the sust, as it's fast acting and will show effects quickly. Here is an example of how i would run sust, cyp and prop, all in a 24 wk cycle. Lets assume my dose for test is about 750mg EW.

1-8

sust 750mg EW, split into EOD injections

9-16

cyp  750 mg EW, split into 3 injections per wk

17-24

prop 800mg EW, split into ED injections

this would be the base of the cycle and I would add and remove other anabolics on a 4 or 8 wk basis