Is there any issues with a baby eating diary from tray that may have leftover chicken?
Is there timtum if babies eat meat and diary?
Technically it might be permitted, if the tray is always washed well and clean, and hot food is never put on it. However practically it is preferred to have separate trays or separate covers for milk and meat, (or at least a separate cover for one of them). This is since there can be leftover residue (or more than that) on the tray from the last time the tray was used, and sometimes the food put down on the tray can be hot.
They should not be given milk and meat to eat, as there is also timtum halev for children.
Asifas Yitzchok who asked this question to numerous poskim including R’ Neuwirth and R’ Feinhandler zt”l, and ybchl”ch R’ Asher Weiss and R’ Nebenzhal shlit”a