You definitely need to remind your parents that, if the dogs are expected to treat your little sister with kindness, she should first gain their trust and be kind to them. Dogs, especially toy breeds who feel VERY threatened by an unpredictable child, cannot be expected to tolerate rough handling, and your sister should always be supervised with the dogs. It's wrong for your parents to threaten to get rid of the dogs - they're the adults, and it's their responsibility to socialize and train both dogs to behave around you sister (and vice versa). Here are some links that you and your family need to read over...

http://sspca.org/Dogs_ChildrenAndDogs2.html

http://www.dogscouts.com/childrendogs.shtml

http://www.dogscouts.com/biteprevention.shtml

http://www.dogsandkids.ca/

http://www.uwsp.edu/psych/dog/lib-prob.htm#kid