Helping my 2yr old cat adjust to kitten an a newborn

I recently took in a kitten from a feral colony I take care of. Vet estimates he is 4 weeks old. I have had him de-fleaed, he is on worm medication once a week for 4 weeks an then once a month until 6months. At this time my female and him are separated. He has had distemper his first one. My Tigerlillymew has been our only cat since she was 8 weeks old. She sees him through a gate she hisses and is terrified of him. She does not growl or swat at him. She is also not a fan of noise, or children as they noisy. Is there a way to help her in time to adjust to Patches who we plan on keeping and helping her when we bring our baby home in 10 weeks. I admit she spoiled silly as far as attention. We revolve our clock around her needs I'm disabled so home with her all the time. I'm extremely worried how she will be with these changes. I been doing an me behavioural therapy with her and play aggression and it has helped some.

Your kitten must be very lonely and he should have other kittens to play with.  Perhaps you could work with a local rescue and arrange to foster some kittens who are his age, or let them take him with their fosters.  Kittens need to learn social skills from other kittens or they can become very obnoxious cats when they grow up.  You will not have time to teach him what he needs to know with a new baby coming yourself.  Tiger Lily is not likely to take kindly to him.  She has been an only female for her whole life and that is her territory.  This isn't helpful to her or to the new little lonely one.  If you had other kittens with him and could enclose them all in one room, that would be fine, or if you could turn him over to a rescue group that has other kittens, that would be wonderful also.  If you really want to keep him, you could get him back when he is older, bu this really doesn't seem to be ideal right now.  I do think it is important to make one of those changes as soon as possible

Thank you for your advice. I just came home from vet with Patches and it seems he may have FIP his belly x rays showed huge amounts of fluid waiting for read. We are quite sad atm