Adoptively

adv. [f. prec. + -LY².] In an adoptive manner; by way of adoption.

1844.  Maitland, Dark Ages, 482. For it is one thing to be so [i.e., one with God] adoptively, and another to be so substantially.

1844.  B. Thorpe, Ælfric’s Hom., I. 259. God, the Father Almighty, has one Son naturally, and many adoptively [A.Sax. gewiscendlice].