Wow! Your children are all very lucky :)
I have birthdays on the 15 and 19/12, so each DS gets one big (by our standards) present for each plus one biggish one from Father Christmas.
DS1 5 on his birthday: Playmobil Pirate Ship
Christmas: A radio CD player and some CDs
Father Christmas: Not sure yet, either a robot or something Imaginext
Smaller presents (I will give a few for Christmas and more for his Birthday): Mega Blocks Police Vehicles set (bargain at 9.90!), Mister Maker Craft set, 2 Imaginext vehicles bought v cheaply on Amazon, Playmo British soldiers boat, Playmo dinosaur set (another Amazon bargain), A big set of colouring stuff, Horton DVD, The Jolly Christmas postman book
DS2 2 on his birthday: Ikea pop-up play tent and tunnel
Christmas: Ikea easel, Paper, Paints etc
Father Christmas: Undecided...
Smaller presents: Playdoh set, Playmo 123 bin lorry, A few books, Timmy Time DVD
I am struggling for DS2 as he has all of his brother's old toys to play with too!