Re these last few posts: of course one can always put a 7 into the tonic before moving to the sub-dom, as the dominant of the key of the subdom is going to be the tonic of the key in which it is the sub-dom, & the added 7 gives that expectation of resolution [sounds a bit convoluted, but I am sure those who know all this follow me]; & it always sounds effective - as does occasional variation, just preceding a change, to tonic-minor.

But these are all frills. There are no major accompaniments which can't be achieved with just T, SD, D [or, if you prefer, 1, 4, 5], because between them these three will contain all the notes of the tonic scale..

And, in a minor key, surprising how much can often be simply achieved with only 2 chords: the tonic + the relative major of its dominant [e.g. D-minor + C-major, the relative major of A-minor]. Try it e.g. in 'One Sunday morning when on my way to Mass'.