I think they look great as brother and sister!
But I will say this... I got Bella when she was 10 weeks old (she is a poodle mix), and I got Harley at 4 years old, and to be honest, I will never have the connection with Harley that I have with Bella. I know that sounds harsh, and mean, but I'm being honest. I think if Harley was a puppy when I got him, it would have been different. I don't know how to explain it. Put it this way, I can clean Bella's poopy butt or nasty eye crusties and not get grossed out at all. But I get grossed out with Harley, even though I love him to death and would do anything for him! Its more of a sub-concious thing maybe, I don't know. Kinda like your skin-kid can get sick and you have no problem cleaning it up or taking care of them, but if it were someone else's kid, it is a different story! It doesn't mean you don't care, because I love Harley sooo much and would do anything for him. I don't know.