interjoin

verb3

1. •
   To interconnect two sets.
2. •
   To join mutually; to unite.

   • […] so, fellest foes, Whose passions and whose plots have broke their sleep, To take the one the other, by some chance, Some trick not worth an egg, shall grow dear friends And interjoin their issues. — 1608
3. •
   To say by way of interruption, to interject.

   • “Oh! you can have no idea of its gaiety,” returned Frances; “and such a quantity of people.” “A number of persons, and a quantity of goods,” interjoined Miss Colville. — 1821