Here's a site I use for general information on bottle feeding,
https://goatspots.com/articles/bottle-feeding/
If they are having scours it's always best to cut back on the milk, or even put them on electrolytes for a day or two. Generally loose stools means you are feeding too much, or there was a too rapid of change in diet.
Goats have sensitive digestive tracts, so all changes should be made slowly. If you are switching between milk and replacer you have to do that slowly. Any increases need to be done slowly as well. I've successfully used replacer, others don't do well using it.