I have twins and then another dd whose birthday is only 3 weeks later.
It gets blooming expensive, but everyone has their own cake, presents, cards etc.
The only shared part is for dt's who have always had a joint party but with plenty of say in which individual and joint friends they want to invite and where the party will be etc. They have quite a discussion about this and agree between themselves.
They are in separate classes too so the list of friends to invite is quite extensive. We always sing happy birthday to them individually too.
No sooner have we recovered from that then it's older dd's and off we go again.
From my pov (and sanity)I wish it was all more spread out.
I wish it could be scaled down and involve less friends. But I have to remind myself that it's not their fault their birthdays are all close or on the same day and I go to great lengths to make them all feel as though they have had their 'own' birthday and that it's not just all lumped together.
I would hate them to look back and not think their own birthday was an individual occasion even though they all happen to be close in the year.