What are my rights as a person who sold a puppy to somebody?

You really should speak with a contract lawyer in your area as these cases are fact specific.

I am sorry for your loss. Talk to the estate attorney about your best options.

Can I be held responsible if my neighbor's dog bites someone on my property?

You could have a lawyer write a letter to the dog owner to, hopefully, get this resolved.

If it is your Dad's dog then he is the one who should go about getting his dog back.

My dog attacked another dog but both got injuries ?

One option is to wait and see what happens.

Do I have to be outside with my dogs while they are in our back yard which is fenced in?

I don't know why you would have to be outside with them but contact the local animal control officer so you can know what is required of you.

Can I use someone for giving me an aggressive dog and not informing me that the dog is aggressive?

You should contact a dog bite lawyer in your area to learn of your best options.

Will I still have the same witness I served a subpoena to if the judge dismissed them from the hearing that sets the court date?

You would be best served by going through all of this with a local lawyer.

So what do I file to obtain the dog back?

Contact the police and/or a lawyer.

You should get the advice of a local landlord tenant lawyer before proceeding.