This breaks my heart,I am so sorry about Tilly she was beautiful,I would not let them outside anymore it is far to dangerous.It is a hard process making outdoor cats indoor,All i would do is put them away when a door is being openend.

And make sure to have Mama cat spayed when she has weined her kittens,Once they get the taste of the outside she will be trying to get out again,and you will have more kittens,Its hard to find kittens homes anymore,Everyone seems to have a few cats and dont want anymore,And that is how so many cats end up on the streets to fend for themselves.

I hope all works out for you,I was there too a few years back i never thought of getting My Alex fixed there all indoor,She got out and kittens came not long after,Its in the cats best intrest to be indoors,I cant tell you how many cats have vanished around my area lately,and its all from Fishers,there taking down dogs and cats.