Visitor visa sponsor for sister

[shivam]

I am planning to invite my sister who is 35 and who has a 18 month old baby. I would like both my sister and her kid to visit. Can anyone tell me the procedure if any different for toddlers of that age. Also my sister has a 13 year old son and husband back home. How easy or how tough is it for getting the visa for my sister and her kid? I really appreciate any info on this.

[Murali]

Procedure is same for each applicant.
read here, she will have to take fill application for each and take appointment
http://www.path2usa.com/immigration/visitorvisa/visitor_visa.htm
She may need a letter from her husband, with No objection for the baby's Visa and Baby's visit to US with the mother, she need to show this letter only if asked during the interview.