[Tracy and Pixie]

I just posted a question about an hour ago about halo kibble among others that I wanted to try with my Pixie. She has gotten to the point where she is not showing any interest in her holistic select small breed and puppy formula kibble. So, I went and got a few sample packs of kibble.
Halo puppy, Fromm puppy gold, Innova puppy and wellness. I put a couple of each kibble in a bowl and she went crazy for the Innova puppy. She seemed to also like the Fromm puppy gold too.
I tested her holistic select with a few kibble of Innova and she just picked the Innova out. How much should I let her eat? I don't want her to get an upset tummy.

I also want to know about canned food. I mix wellness puppy with merriks puppy plate and I was wondering if it is okay to switch up merriks flavors. Will it upset her tummy? Im sure that all the flavors are for all life stages so I thought switching it up may be good so that Pixie will not get bored. She is 11 wks old and is about 2.4lbs. I feed her canned 3x a day about 1 heaping tsp. and kibble if she touches it. As u can see from above she has not really touched it other than the Innova puppy today.

Any info or advice is greatly appreciated.