[cypher]

What cage do you currently have your syrian in?
It's fine to have dwarf & syrian hams in the same room that shouldn't be a problem at all but dwarf hams do still need space, they are very active little things, still need a big enough wheel (20cm usually) so you have quite a bit to fit in the cage in spite of their size.
Pairs do generally get on better in a slightly smaller cage than a single dwarf as it gives them less to become territorial over but many pairs fight as they mature & do need to be separated which would leave you needing two cages, possibly slighter larger than the one you have now.
You need that spare cage ready from the start really too as fighting can break out at any time & escalate quickly.