Must you obtain a FCC License for family use (including children) of two way radios with GMRS?

"If you operate a radio that has been approved exclusively under the rules that apply to FRS, you are not required to have a license. FRS radios have a maximum power of ½ watt (500 milliwatt) effective radiated power and integral (non-detachable) antennas. If you operate a radio under the rules that apply to GMRS, you must have a GMRS license. GMRS radios generally transmit at higher power levels (1 to 5 watts is typical) and may have detachable antennas."

On channels 8-14, the radio is only operating under FRS rules (since those frequencies are not even part of the GMRS frequncy list) and would be legal without a license. If the radio will operate at a low power level (500mW or 1/2 watt ERP) on channels 1-7, this would also qualify as FRS without a license but I would check the owners manual to see if there is a low power setting and if it is below 500mW, most likely it is. Channels 15-22 are strictly GMRS and require licensing. You may be able to download a manual somewhere.

Yes. Under all circumstances of GMRS operation, a license is required.

to operate legally yes.