Dusting once or twice a week in the winter (due to the dry heat) is enough for your chins. In the summer time, 2 to 4 times a week is best ... daily, during high humidity. Grooming is not only for show chins. All chins can be groomed, but you do need to learn how to do it properly first.
Feeding your chins in separate bowls is best ... if you have one that pushes the other one away or tries to eat it all ... often one will bully the other one. I always try to make sure the food bowl has food in it ... even if I have to feed 3 times a day. 2 table spoons is only a guide line, each chin may eat less or more ... you have to just learn how to judge it for each chinchilla.
Do not hold your chin at the base of the tail ... hold it about an inch from the base of the tail. It is best to hold it between two fingers of the same hand the chin is sitting in. Always support the hind feet of your chin ... if you don't, it will think it is falling and struggle to get away. You hold him by the tail firmly but gently.
Jo Ann