Answer
Rosie:
My older dog did the same thing when we got our first puppy, 4 years ago, and again thus year when we got another puppy.
She would ignore the puppy for about 3 months. Then she would start to interact with the puppy. Kind of reminds me of a bachelor uncle that doesn't know how to act around babies, but thinks toddlers are fun.
Your Dane may stay aloof, or she may interact more with the puppy as he gets older. It depends on her personality.
Just supervise them when they are together and don't let him harass her. If he does harass her, allow her to correct him, as long as she does it in a controlled manner.
Belgian:
Dogs are individuals. They are NOT all the same any more than people are! Some dogs will warm up, others won't.
You don't have anything to worry about since the senior dog isn't attacking. Just don't leave them unsupervised and do NOT allow this puppy to harass her (which it will do when it feels more at home.)
Nobby:
Respect her, older dogs are often nervous around tiny puppes as they are half expecting an angry protective mother to appear and have a go at them!
Keep them separate, I'm sure as he gets older she'll be fine.