Need Help With Mama and Kittens

Hello, we have similar issues - in March of this year we were given a 6 year-old pregnant cat to care for during her pregnancy which has turned into unspecified, long-term.  We don't have specifics about her history but are under the impression that this was her fourth or fifth pregnancy; this time she gave birth to three kittens and one died two days afterwards we believe from starvation - he was always wondering away from the mother and she did not guide him to feed properly.  At about four weeks following his birth, the surviving male kitten started drinking kitten milk, eating wet and dry food, taking tidbits of chicken, cheese, and other treats whilst nursing on and off.  He is now about 10 weeks old, eats very well and having his nutritional needs met, sleeps well and is overall a happy, chubby, little ball of fur who will nurse for comfort or to sleep at night.  On the other hand, his sister is still nursing constantly even after having her fill of milk.  We had the most difficult time for her to drink independently and it was when she was seven weeks old.  She refused to drink when we put a little dish to her mouth or a tiny bit on her mouth to lick - she just did not want to take the milk so I thought to purchase a glass dropper to feed her.  For one and a half weeks it was dipping the dropper into a small dish of kitten milk and patiently feeding her until she was satisfied; and for every two hours in a day it was not easy.  I was concerned because she was so tiny - half her brother's size.  She finally started licking the milk on her own and drinks quite a bit (three times the amount of her brother), but as she is ten weeks old and growing, I think she needs more than just milk and she is still small. She refuses to eat with her brother when I serve his wet, kitten food or to take tiny tidbits of meat or cheese.

The other issue is similar to the mother wanting to go outside, making loud noises late at night, rolling on the floor, taking the position of preparing to mate even though there is no male in the home (he was brought with her - the father of the kittens - but jumped out of the window at night the second week of his arrival).  For the past few weeks, the mother spends most of her time on the window sill and a few times we have found her perched on the window when it is ajar - the other day her son was also perched on top of the window - we think he is copying her - but it was very frightening to think that he could have fallen, undoubtedly to his death.  As we live in on the top of a three-story building, we are afraid to let her out as she will either not return nor will not be able to find her way back.  We did not think of having her spayed as it would be expensive and am not sure if the owner would approve of this either.

I would appreciate any practical advise here.  Thank you!

How old are the kittens?  When her son is old enough he will impregnate her.

There are numerous reasons to spay a cat, especially an older cat.  I copied the following from and article located at the top of the forum.

The Benefits of Spaying a Female

Spaying your female cat will prevent unwanted litters. That is the fundamental issue, because if your cat gives birth, you are the one faced with the task of finding new homes for the kittens.

Here are some added benefits to spaying your female cat:

Prevent tumors and infections of the ovaries and uterus.

Greatly decrease the risk for mammary cancer.

Spaying a cat before she goes into her first heat is best, but even spaying at a later age will dramatically decrease the risk of mammary cancer.

Avoid the hassle of a female cat in heat.

Cats in heat can be very vocal and will attract a great many male cats. If you think you can wait out the heat cycle, you're in for a surprise. If the cat does not mate, she will keep going into heat every few weeks.

Please contact the owner/cat parent and see if s/he will consider spaying her.

For the sister, have you taken her to a vet to be seen?  There are parasites that will prevent her from gaining weight.

Thank you both for your replies.  No, I haven't taken the kitten to the vet but will do so (am new to our area so I will enquire); what parasites do you refer to sister?  It didn't occur to me that the son could mate with his mother (what a disturbing thought); at about what age are they sexually active?  I will also enquire about the cost of spaying and will be in contact with the owner in the next day or two.

Some males become sexually active at 4 months.  I think that is considered early but it has happened.

I was thinking she may have worms of some sort.  They can get worms from fleas and mosquitoes.  The vet would be able to tell you more.

Neutering is often cheaper than spaying, so if he doesn't have the money to spay (one reason people don't spay) you can have the male taken care of - it's cheaper.  You may want to neuter the male anyways.

 [article="0"]Spay And Neuter Your Cats​[/article]  

From your description of her behaviour, the mother cat is already in heat. If she goes out she will definitely come back pregnant again, as that will be her sole aim in life. Regardless of the owner, if you can do it, I would spay her as soon as possible. It is great that you are looking after these cats for someone else - it is always a difficult thing to do.

Yes, the mother cat's behavior indicates she is in heat. She needs to be spayed rather than having litter after litter. She will be healthier, live longer, and it will put an end to the annoying behavior cats demonstrate while in the heat cycle.

Kittens can be spayed and neutered when they reach 2 pounds, which is usually around 10 to 12 weeks old.

I agree that the female kitten needs a vet visit. In the meantime try mixing her milk into the wet food to make a mush. This may be more appealing to her. Also moisten her kitten chow with the milk to make it softer. She needs to begin eating so she will grow.

Can you put a screen in the window so the cats do not fall out?