Service Berry Jam Help

This year I harvested about a gallon of service berries. The flavor is mildly sweet but the texture of the berry is a bit dry and full of seeds. I'd like to make jam or jelly from the berries and wondered if anyone out there has done this before.

I've already cooked, mashed and put the berries through a food mill to remove the solids. I now have a thick syrup-like extract from the berries. By itself it's good and I could make a jelly from that, but I'm thinking of adding raspberries for some acid and more flavor. I can thicken with gelatin as needed in the final product. I don't want to add refined sugar which makes it a more difficult process.

Any ideas?

Raspberries would be an excellent mix :D