The ELS, WELS, and LCMS (of which I am a pastor) have no formal relations with ELCA.
Yet...they consistently reject overtures to declare them apostate and heterodox in Convention.
Do you agreed with such “fraternal inconsistency”; a way to keep the peace among members?
I, too am LCMS and quite active in synodical efforts (tho, I am a parish based “whiner” according to my DiP).
As student of history, I have studied the on-going effects of the Prussian Union. e.g. It certainly DID cross the Atlantic with Walther...