I think I am going to put some pressure on my sister to allow her baby daddy to see their child?
Why would you put pressure on your sister to allow for something like this?
I am of the opinion that it is best to put yourself through hardship before your brother/sister.
You shouldn't get involved in family matter involving children with the partners. She may think you're overstepping your boundaries and get upset with you. Try offering up a pros list on why children getting to see both parent's can be a good thing.
Some advice given to me: "If feeling pressured don't get into a relationships." She deserves it for being in a relationship with a loser.
It just may be best for you to allow for your sister to handle her own relationship with her baby daddy. If you continue to intervene and give your opinion like this you may annoy your sister. Just being there for her is probably the best course of action.