If you want to continue milking the nanny post-weaning it is better to remove the kids early, milk her twice a day and bottle feed the milk back to the kids. She will keep her milk production up, if the kids are suckling she will adjust "her" production to their needs . and these will be less by three months than they were at 2 months..., so you can already use some of the milk and the kids get what they need. Also if you have one with triplets and maybe not enough milk, and one with twins/single with excess milk you can ensure that all kids get what they need - easy! Also kids can be very rough on the dam's udder... if milking the nanny you can quicly get a feel for her udder and anything not quite right (mastitis) can be nipped in the bud so much quicker.
My kids live in a pen of their own, removed from their dam at 4 to 7 days, depending on how well she is feeding them, how busy I am etc etc, now it is just a matter of hanging up the bottle rack and two minutes later it is all gone... happy kids, happy me (though I still have the washing up to do afterwards...). Kids are VERY friendly to humans that way...