I'm with Winterstale, make it by the pitcher. Something with a cap or lid so you can shake it. Trying to make them individually is just too messy. Adding the rum later means you can adjust the alcohol with every drink and also use a reasonable size container.

The Capt doesn't really drink them and I rarely have more than two. Love them but sooooooo sweet. So for to avoid the mess and an open Coco Lopez container I make the pitcherful on a Friday and easily lasts the weekend in the fridge. Just need to be able to shake the hell out of it before pouring.

Pour a couple and pull up the Soggy Webcam.