Issues with new kitten

I rescued a stray preggo kitten almost a month ago now. Not sure of her age, thinking 7-8 months. She lost her kittens. My other cat does not like her. This kitten is play aggressive I think that is what you call it. She will use my hubby and I as a chew toy and you know how kitten teeth are ouch lol. She chases my cat around the house. Attacks her sometimes (no blood/injuries). She cries a lot too. Last night trying to sleep she woke us up ever 1-2 hours. We are not sure where she came from but she loves to snuggle and be a lap kitty too. She still has milk so if I rub her belly that relaxes her sometimes. I'm just on the fence with it because I feel like I turned my other cats whole world upside down. She is my baby and she gets really stressed with grace the kitten is chasing her around. The kitten is not spayed yet but I plan on doing that next month. Any tips or help would be great.

Here is a pic of Grace the kitten. She looks cute and innocent there lol

I believe her crying is quite normal if these are her first days with you. She's probably just a bit scared of the new surroundings but my experience has been that after a week or two they adapt. 

Regarding your other cat,  how did you introduce the cats to each other?