Hi - WELCOME to YT
. So sorry no one has yet answered your question, don't know how it got missed.
You sound like such a good yorkie parent - providing a lot of activity and stimulation. Since your kiddos are so active, it may be that they do require more than an average amount of food, so I wouldn't hesitate to start giving them a bit more food if you feel they are thin.
Here is a feeding calculator if you want to try it out. Otherwise, just feed to body condition.
It would be just fine to either give the canned alone or with kibble. Since it's a supplemental feeding, I'd start out small and see what happens to their body condition over a couple weeks and then adjust from there.