Hessians have upper hand around O3/CB JH ... Mollys can build their base somewhere around in CB. Rest of O3 is 50:50 hessians/sairs.
Why to be alied with Mollies...
Since hessians already own 2 bases in O47, cleaning of O49 is just matter of time. And gues who is living next to O49 from the other side? Mollys yaaaay.
With Mollys in CB next to JH into O3 we (hessians) can get upper hand even in O3.
Mollys are also nice source of cheap gold and they can keep annoying BAF far from our bussines in O3.
Take it from different view. There isnt just OC aliance vs sairs. There is OC aliance (dragons, lib unlawfuls) and Hessian aliance (rheinland groupes) vs sairs. Those two aliances are fighting togeather against sairs as equal partners. Mollys arent stupid bunch of empty heads, they know they need help with sairs and since there are at the moment 2 huge forces even alied togeather with same goal, only what they need is just work with one or even better with both of them. It is just on their decision if they will be more Hessian or OC friendly and since OCs are little bit colaborating with Bretonian goverment... I think more acceptable way for Mollys is Hessian sphere of influence.