Fascinating colors. Okay, so mom is a brindled harlequin, although she does have eye rings (a proper harlequin shouldn't). You can see all the mottling of colors in her coat:
dad looks like a dilute blue/fawn tricolor, and mystery baby also has harlequin. Look at the patches of color on his side:
The eye rings say agouti, but they aren't evenly sized rings, there's some harlequin mottling there. Same with the feet:
The dilute gray shade looks like blue to me. He may be a harlequinized opal (blue agouti), but look at the hair closeup:
No agouti rings on this patch, just looks fawn to me. Which would point to blue/fawn harlequin, but the overall look is still opal (blue agouti). Especially with the agouti eye rings, my guess is that he is a harlequinized blue agouti.
As to the odd coat on dad, the waves are caused by the recessive wavy gene, found occasionally on Rex rabbits. They were bred for a while as a breed of their own, called Astrex. Lovely.