I am a step father and I'm trying to find out the best way to go about getting full custody of my step daughter. I my wife my daughter and I are all from Texas but since I'm in the military we live in Maryland. Do I still need to file for custody in Texas. Would filing for abondonment be appropriate we have had absolutely no support from him since our daughter was 2 months old and she is now about to turn two years old the last time there was contact between us and the biological father was through one Facebook message four months ago and one phone call three months before that not asking about the child. What would be the appropriate way to go about getting custody of my step daughter.

You need to adopt her legally. Only a parent can have full custody - not a step parent. Consult a good family attorney in Maryland to see how to go about this legally.

Your only real choice to to adopt.

To other issues, the attorney doing this adoption will need to contact the bio father and get him to sign over his rights for the adoption, without that it will be harder.

Abandoment is a strange thing, in many places there is no real law expect to use an a reason to file for changes in custody. In many it is just not paying court ordered child support.

So since the bio father is not paying the court ordered child support ( assumes there is a court order since you said he was not paying) If there is no court order he really does not owe anything in many places.