Newborn kitten not pooping

I’ve been feeding a 7-8 month old kitten for the past 3/4 months. She comes to my backyard with 2 other older cats. I realized she was pregnant about a month and half ago. Tried to catch her but was unsuccessful. She went missing about 10 days ago and this monday came back with 2 kittens. One of them had an umbilical cord injury with maggots infestation and had to be euthanized. We took both of them in and the mom followed. The surviving kitten hasn’t been pooping for as long as she’s been with us (about 72 hours now). We have been stimulating her and she pees every now and then. But no poop. Took her to a vet last night and the vet helped get some poop out but is not sure how much is in her still. I’m okay with surrendering the kitten to professionals but I don’t want her to be separated from her mom who’s feisty. They are both in my house. The kitten is latching on the mom but I am not sure if the mom can produce milk given the stress she’s in. I see the mom licking her every now and then. Tried bottle feeding but she is not taking it. Any suggestions would be appreciated.