Make quilt for sister # 1 first ,then work on sis # 2 quilt and make what you want,cause if you try to please sis as well as boyfriend then it becomes a chore and just know that you are making something from your heart and with lots of love,maybe a pattern with a meaning of sisterly love ,like "SISTERS CHOICE"? But the choice being that of the makers not the one reciving the quilt,I say this becuse I have been where you are and if sis doesn't quilt my quess is that she has little knowledge of time as well as money that goes into making a quilt.Remember that you should enjoy your craft!