That’s great that you’re getting yourself set up to be able to play with the church group!
You can do it !
I’ve no idea how/if/when they use the 2nd chords w guitar…
Yall’s band appears to be more ‘sophisticated’ than ours was when we played in church! (We weren’t playing Contemporary…)
If it were me, I’d try playing along with the YouTube vids and just using the regular old Amaj or Dmaj (you may have to toy around with different chord voicings/different locations on the neck to get the sound you want) and see how that fits it. It might be fine. If it doesn’t sound right, then I’d try swapping from those various chord voicings of the A & D to the appropriate A2 or D2 when it was called for and see how that sounded and compare it to what you did before. Maybe even record it and then compare the recordings and see what you think.
My understanding is to do A2, you would basically be taking the 3rd chord tone out of the chord and substituting a 2 tone. Like for A it wouldn’t be the standard A, C#, E (1,3,5) - instead you’d use something like A, B, E (1,2,5). Depending on where you play your A, your frets will differ. For me, I often play the 2245 (or just 224X) for an A chord - to switch to the A2 from there would be easy, bar the 2 fret across 3 strings for a 222O - notes would = A,E,B,E (actually, don’t even have to play that open string, can do 222X). Same thought process for the D2.
Not sure if that helped any, as I didn’t answer your original question, haha! Best to you on your project!!