Why does it upset me so much?

both my daughters birthdays are 5 days apart and i find that most of the family (who are meant to love my kids equally!) turn up on my youngests birthday and leave presents and cards for my other daughter instead of visiting her on her birthday. They may have their birthdays close together but call me sensitive but surely they should both be entitled to the same attention on each of their special days? My eldest has cerebral palsy and is usually her birthday no-one turns up and is fact her that loves to see people,am i being over dramatic,should i let it bother me so? I do say to everyone but i hear all the excuses!