Wonderful that you and your sister have so much fun and that her body turns you on. Keep fucking her as often as you can and keep pumping your seed deep into her willing body as I'm sure that she enjoys it too.
My first wife was 20 fat lil slut.i was 21.i new she liked one of my mates .one day we was fishing and I told him she liked him.he didn't no wot to say.i asked him if he liked her he said I not really thought about it .two days later we was fishing again .and I mentioned it again .he said she is attractive nice plump thighs and good tits on her .I asked him if he would fuck her .he said he would but his wife musent find out .so I foned home and said do your hair and make up on.plus stockings and suspenders belts open knickers and bra.plus high heels as iam coming home lay on the bed fucking your self.i told him wot to expect .we planed it that I would go in bedroom and fuck her ten minutes later he comes in .naked gets on bed and starts sucking on her nipple I pull out of her and leave bedroom before I get to door he has mounted her and fucking her I was watching.he fucked her really good .he became a reguler fuck for her 4 times aweek