any chicken raisers ....... I have a question

Hello,

I need some adivise.

We would like to add some more chickens to our flock. We have 18 Bantam Chickens at present.

We did have 25, but in the last few days we lost 7 chickens. They were free ranging, and we thought something was getting them during the day, but when we found 3 less this morning when we let them out, we realized that something was getting into the coop at night. We have a screened in yard with a covered top, so we were leaving the little side door open ........... poor things. Somehow something must have been able to get into the pen area.

We've fixed every place we can think that something can get in and will always close the side door from now on. My son is going to try and sit up tonight to see who the culprit is.

Anyways ............... sorry about the long narrative.

We would like to introduce some new chicks to our current flock. Is this possible to do? Is there a good/best way of doing it?

Will the old flock except new chicks? Would they accept them if we "planted" fertilized eggs?

I'd really prefer to get full sized chickens .... will they mix with bantams OK.

I'd really appreciate any help.