] Only Lady Catherine seemed pre-occupied with dynasty building. We hear nothing from Colonel Fitzwilliam's side on this. Only indication we get is that he marry with money, no mention of family?

We don't know that. We know nothing about Fitzwilliam's parents or Darcy's. Or Darcy's cousins or their marriages - except that Colonel Fitzwilliam is not married.

All we know about Georgiana is that that Darcy was thinking of Bingley. But perhaps that had a good deal to do with Mr. Bingley's character. Since Colonel Fitzwilliam is so much older, he seems an unlikely choice for a dynastic match.

] But why couldn't Darcy just have referred Elizabeth to an un-named solicitor rather than a named co-guardian for verification?

I can't figure out why a solictor would know anything. The point was that secrecy about the affair was of the utmost importance. Few if anyone would have been told. And Colonel Fitzwilliam was at hand (rather conviently) for Elizabeth to verify in person. Writing for confirmation would be considered inappropriate anyway.

] Elizabeth never checks with Colonel Fizwilliam as to the particulars and we do not hear from him again on the subject of Wickham.

She doesn't feel she needs to. She feels that the reference alone stands for the story's veracity.

] I suspect that Ms. Austen did not think overly hard on a secondary character to her novel. However, in case she did, maybe she was suggesting that these two co-guardians offered different talents and role models to Georgianna.

Darcy was 23 when his father died. That is realitively young. He is trust worthy but perhaps his father felt that he might want or need another to help him through. It would lighten the burden of being totally responsible. CF is Darcy's elder and apparently his friend.

I always imagined that Darcy made most of the decisions and Col. Fitzwilliam played a supervisory role. He was there to confirm and offer additional advice.

] For example, at the Netherfield ball, Darcy was disturbed by the unsolicited introduction from Mr. Collins but mabe the Colonel would have ignored the lack of societal convention and chatted pleasantly with the man about Lady Catherine.

I highly doubt that Old Mr. Darcy felt his son inacapable of doing his duty. Darcy is always shown as having treated his own circle impeccably well. You imply that his father saw flaws in him that needed correction. Darcy himself denies this when he says his parents spoiled him.

I can imagine Mr. Darcy thought his sober and intelligent young son amply qualified to take over and perhaps this gave him some comfort before he died.

] If Ms. Austen thought a lot about Georgianna, maybe she assigned two guardians because she wanted both perspectives; love and family devotion from her brother and little liveliness of manners from her cousin.

Then Colonel Fitzwilliam has not done his intended job. The girl is beyond timid. I think Austen likes the Colonel and wouldn't make such a criticism.