I think
Ian is a fine name, tho a bit boring.
My co-worker just married an
Ian, and he is in no way wimpy - full beard, hiker, works for an outfitters/sports store. His siblings are
Heather and
Brian. I think
Brian is to similar, but it made hand-me-downs easier, just add a BR in front of
IAN, hehe.
I'm not good at sibsets, but most names would probably work since it's such a common name. Maybe
Melanie,
Claire,
Cole,
Tristan, etc. To spice it up a bit you might try some less common Scottish names, like
Alasdair,
Callum,
Conall,
Fiona,
Lilias, etc.