Domestic Violence: Advice On Domestic Battery And Subpoena

I have been charged with 2 counts of domestic battery in Florida. It was with my adopted son who was not living in my home and his half brother not from my wife but my adopted sons father, one is 18,the other 22. who at the time was renting from my wife in our house. the charges are florida statutes sections 784.03(1)(a)\
My first question is how can I be charged with domestic battery against someone who is not related to me or my wife? The second is that the two have moved to Arizona to be with there biological father. There will be a subpoena issued for them to return to Florida as witnesses in the states case. But they do not want to return to Florida. The two assume that if they do not show for the trial that the case will be dropped. They have asked the state to resind there statements but were told they would have to return to Florida to do so. Question is then, if they refuse to return to Florida after recieving subpoena will they be in trouble for not retuning? And if so what? They say they want it to go away but the state says it is out of the boys hands andthere is nothing they (the boys) can do. Is this true? I have an attorney but the cost of the trial will be more than I can handle. So it would be nice for this to stop at pre-trial which is this Monday the 10th. So far I have lost my job and am currently seperated from my wife because of this. I am 47 years old and have never been in any kind of trouble before so I do not understand why this is happening this way. Any help would be highly appreciated. If you would like more details etc. let me know. Thank you in advance for your time in this.