Meeting my boyfriends family!?

ok i'm meeting my boyfriends OTHER SIDE of the family, i've been with him almost a year and haven't been able to meet his gran,aunt and cousins till now as they live abit away from him. its his 18th and wer going to visit! i bought some new black skinnies but i'm not sure what to wear with them, high heels and a nice dressy sort of top, but still casual ORR white pumps and jst a normal top. im 16 years old btw(: x