All species of mollies will interbreed - same with all livebearers, if their species is the same they will interbreed, mollies can breed with guppies and endless (though rare), endlers and guppies is more common, swordtails with platies, so on...
But it's more likely that they will stick to fish similar to them, so that's why your creamsicles won't interact with the Dalmatian. What you should do, if possible is return one male and the Dalmatian and come home with 2 female creamsicles.
I've noticed that mollies are some of the more aggressive livebearers and unlike guppies which can usually be okay in pairs, they absolutely need a higher female ratio to males, I'd suggest atleast 3 females per male. I had 2 pairs of pandas/gold dust together for quite some time and my males were always chasing the females down pretty aggressively, when I added 3 more females of the same type they all relaxed and while I still saw a lot of chasing, it wasn't nearly as bad as it was before.
I should also add that if you had 0 females and all males this would also help lower the aggression a good amount and keep you from ending up with a severely overstocked tank from all the fry. Molly fry, along with "fancy" guppies (guppies that aren't a certain strain like what you'll find at the pet store), are some of the hardest fry to rehome. Unless you have a rare strain, your LFS will likely only take them as donations, if they take them at all because they are so common and easy to breed. -just a thought-
