Special needs parents? (Severe cases)

My boyfriend has a special needs 5 year old son.. will never walk, talk, feed himself , hold his head up, always will wear a diaper. Basically dependent in every aspect ( similar to a newborn) Curious how your life is with other children who aren't special needs. How has it affected your way of parenting all children ? We are currently trying for our second. ( I have a son as well)