I can't imagine that the children don't see enough of each other. They live together, see each other daily, and will always be close. There is a big age difference so they aren't going to playmates, but that doesn't mean you have to worry about them. As the little one gets older and can do more things, they will engage much more. Perhaps you are worried that they don't do a lot now? But the little one is only 1! I am sure that, as she grows, she will rely on her big sister.
I know how much my husband missed his children from his first marriage, and how little time every other weekend and 1 night a week are. I think it would have been wonderful for you to give the dad an extra night with the little one, get some rest yourself, and have some special time with the older one (which I realize you get on the visitation schedule as is, but still). Sometimes an unscheduled break in a tight schedule is a benefit to everyone else.
I think that you are hurt that the dad seemed to reject the importance of your child's sister. She's not his child but you felt she was dismissed by him. Perhaps he didn't mean that. Even if he did, I'm not sure it solves anything by expecting him to acknowledge the needs of the older child. It's wonderful that he loves his daughter and wants to spend more time with her, and it's nice that he saw that you needed a break. So many men don't do those things and you should celebrate that this one does.
Maybe it would be better to say that the two most important ROLE MODELS are you and him. It would be great for the children to see you both cooperating and helping each other out with the child care on an as-needed basis and not just on the visitation schedule.
These sisters see each other an awful lot, more than the little one sees her dad. As much as you worry that they will not have a bond, imagine how much the dad feels about the need to have a bond with his daughter. Imagine how much she will need a strong male role model as she gets older and starts choosing men for herself. Let both girls see that a man can be a nurturer and a giving person.