@hypolite Hello, thanks for your reply & interesting info.
Oh, well that's most disappointing, but certainly fits with my frustrating experience that nothing at all happened after i clicked Submit.
No but you see, this was the reason i made my OP... this method looks like it works from the Friendica perspective, in that the DM "sends" ... but that's no good because the essential second part of the process NEVER occurs, as i said in my OP -- the DM never arrives in Masto, thus defeating the entire purpose.
Tbh i'm feeling a bit distraught about this now, because in other respects, having spent last night & all today inside my new Friendica account & learning how to drive it, i have really come to like it & could definitely imagine switching from my Masto Instance to this one as my new daily default Fedi account. However, it's pretty important that i can still send DMs from here to contacts in Masto, so if i can't [& as of now, i still cannot], then it jeopardises the possibility of using this account fulltime. It's a bit sad. 😢