And, at the very first sign of danger, old Andrew would clear out to the Continent, shut up the girl, get rid of that insured package, and cut all future communications! In the long three years, the girl might die, be estranged from you, or perhaps fall into the hands of some foreign fortune hunter.

Human nature--woman nature--is a mutable quantity.

But once we are in communication we can provide for future correspondence in any event.
"And you, Anstruther, would be defeated in recovering the hidden property of the Crown.

Moreover, these two Frasers are the only heirs-at-law.
"Who knows what might not be done for a million, when a beggarly fifty pounds will buy a death certificate in many a little continental town ?" They were all gravely silent as Murray soberly clinched his argument.
"It is idle not to believe that old Hugh Fraser Johnstone laid out his brother's whole future course! He certainly has trusted him with his stealings, the lost crown jewels! He trusts his child's whole future to the care of these two cold Scotsmen, and gives the heiress over to old Andrew, to keep her safe from Madame," Murray bowed, "his only living enemy, and from all the other relatives of his long-hated dead wife.
From your own disclosures and Madame's own words, we must all fear that her first appearance would be the signal for the spiriting away of Nadine until the minority is at an end.

And it might invite some secret crime.