Which preposition to use with copartners

in Occurrences 3%

Perhaps intimate acquaintance had also tended to enable him to appreciate, with greater accuracy, the meretricious genius and artificial tastes of his copartner in The Liberal.

of Occurrences 3%

"The only mirror of extreme annoy;" But not alone thou diest, my love, for I Will be copartner of thy destiny.

for Occurrences 1%

Whether Mr Hunt was or was not a fit copartner for one of his Lordship's rank and celebrity, I do not undertake to judge; but any individual was good enough for that vile prostitution of his genius, to which, in an unguarded hour, he submitted for money.

Which preposition to use with  copartners