How many did you get? They need to be kept in groups of at least 6, which will also be about your max bio-load for a 10 gallon tank. They are pretty active and prefer larger tanks (15 gallons, or 24 inches long), but otherwise they are a pretty good choice. They can do acidic or alkaline pH ranges and are hardy, like your betta. No long fins to be nipped at, and not nippers themselves.
You said they all died once before? Do you know why they died? Bettas can live in sub-par conditions a lot longer than most other fish. If you don't have a water test kit, you'll need to get one if you have other tropical fish, especially with a fully-stocked tank (I'd advise against test strips, they can be pretty unreliable. Liquid kits are a better option). You'll need to establish bacteria colonies to keep the water parameters in check, and then you can determine a water change routine to keep the ammonia from poisoning your fish and the nitrates from building up too high.