The danger is that as they grow and demand more milk, if she can’t keep pace with demand they can bring her condition down, damage her udder, possibly leading to mastitis.
If she’s managing well for now (and is still doing so on Friday before you set off, with all three lambs nice and full, not blaring and none of them constantly running under her trying to snatch a suck, or trying to snatch a suck off any other ewes), has a good condition score for her type, and is on good grass and lots of it, she will probably be fine at least until after the wedding. Once you’re back, either start topping up anyway, remove one lamb, or watch her and them like a hawk for any signs she or they are struggling, and act very promptly if you see any. In my experience, by the time you see any struggling, the damage is done, and a poor ewe who takes a lot of recovering, mastitis, lambs which suffer a check and take a longer time to get fit, some or all of these things are already inevitable. But some ewes will manage, so it’s a judgment call.
Have a good wedding, and best of luck with the triplets and ewe