Since you PCSed to Germany you need to work towards bringing your family over there. Your Commander and NCO will be tracking that. Germany is NOT a family restricted tour, it is 100% command sponsored. Yes, you will have to stay in the barracks until you find family quarters in Germany, especially if there is a waiting line for on-post housing. I know for a fact there is plenty of off-post housing there! Usually even if you are a Private E-1 you are authorised to live off-post IF on-post family housing is not available.
You need to find a housing, get passports, airplane tickets for your family (that is usually a part of levy briefing) and bring them to Germany. Once you sign a lease go to finance and they will start your Overseas Housing Allowance (OHA) and pay you a one-time Move In Housing Allowance (MIHA). You will have to move out of the barracks and make all effort to bring the family! Until finance starts your OHA you will be drawing BAH for Ft. Riley. While you are in U.S you will ALWAYS be drawing BAH based on your permanent duty station which is Fort Riley while you are in process of getting housing in Germany. remember, you are not moving your family anywhere else in CONUS, you are moving them OCONUS to Germany. On the day they arrive to germany you must go to finance and ask them to start Cost of Living Allowance (COLA) for your family members. Enroll them into local TRICARE and if you chose it, TRICARE Dental.
The only one way you can leave your family in the US while you're on orders to Germany is a VERY significant reason like divorce, extreme health issues requiring US-based treatment not available in Germany, or if your spouse is in process of getting US Citizenship and simply can not get a US passport to join you in Germany.
If you are not bringing them there (which sounds very weird!), then you will spend 3 years in the barracks because Finance is NOT going to pay you huge european OHA if your family is not coming. I saw that happen before and it's better to tell your Commander upfront they are not coming. As a married Soldier you are on a 36-months Command-sponsored tour.
The only place they are going to be at is Germany! Do not plan to move them somewhere else and expect to get a higher than Ft. Riley BAH.