wowsers!!
i hope things go smoothly for them.
a friend of the family had QUADS, they are now 6. 4 boys!! They did go through IVF and had 2 embryos transfered and then both of them split! (so they have 2 sets of identicals)
i know she was hospitalised for some time and she had them at 32weeks (which i think at quads they aim for about 34weeks)
They had lots and lots of help in the early days between both parents and sister, SIL they worked on shift times and had it all up on boards who did what and was due for what.
They look back now and wonder how they did it but with lots of support they got through the early days!
all the best to your SIL