Just reread this and realised it's an essay sorry!!
Congratulations on your babies! I'm still bf my 9 month old twins, I ebf bar a few top up feeds in the second week due to T1's weight loss due to my milk being slow to come in after my section. My DS1 was 21 months old when my twins were born and I was a bit worried about how things would work. I started tandem feeding as soon as we got home from the hospital which I think was the most helpful thing we did as it saved so much time and meant that I got plenty of cuddles even if one baby wasn't feeding. DS1 could snuggle next to us on the sofa and I read to him or we watched cbeebies (my saviour!). I used a tandem feeding pillow too, although it was crazy expensive (£60 I think!) it was absolutely invaluable until they outgrew it at 6 months, now I use a normal v-shaped pillow plus an extra normal pillow each side to prop them up, lol.
I fed my DS1 on demand but early on decided that this wasn't going to work for me this time so instead I fed when one baby wanted but always fed the second twin at the same time, I did/do the same at night even now so if one wakes up I feed them both which has kept them on very similar schedules. I also encouraged a schedule by feeding them when it suited me/DS1's schedule and they seemed ok with that which really helped me. They have a boob each; in the early days I used to swap them each day but I kept losing track and it didn't seem to make any difference anyway so I soon settled into the greedier twin having the boob with the quicker let down and now that's how we always do it.
I wouldn't say it was easy (sometimes it was reeeeeally hard!) and they still are nowhere near sleeping through but it is do-able. Having a DP who can help at night with nappy changes etc when they were tiny swung it for me and allowed us to avoid too much crying while one waited for me to change the other :)
Our routine was roughly this, and still is actually although obviously there's fewer feeds and some food in there now too:
*Babies wake, feed.
*Get all kids up and dressed.
*Breakfast for DS1.
*Feed babies before going out for a walk/shop/feed ducks etc to let DS1 blow off steam while the babies nap.
*Home to feed babies, eat lunch. Play.
*Put DS1 down for a nap, feed babies, let them sleep on me (still do).
*Wake DS1, feed babies.
*Play, dinner for DS1, play.
*Bedtime routine for DS1, feed babies: for the first 4 months settled we them downstairs with us as their bedtimes varied too much, after 4 months we settled them in their cot upstairs. (we swapped them into 2 cots at 6 months but they're still in our room now)
*Feed on demand over night.
Good luck and enjoy the journey! :)