Help please with spellings ??

[supermum98]

My ds has 3 x SPLD (WM, processing speed, hand-writing speed). I am struggling to get him to retain what I think are technically irregular spellings eg. materials, essential, varieties to name but a few. We are up to twelve repeats and no sign of retention. Have got him to write out, sound out and even used a sand-tray.
I notice on the 'Action' year5/year 6 SPLD tick list, difficulty in retaining irregular spellings is a criteria. How many repeats would you suggest constitutes a difficulty? Any help our idea's much appreciated. How many criteria do you have to have to go on 'Action'. I would like to know one way or another by the end of year 6 whether he should be on SENS register, school thinks not. The trouble is he scored over 12 .10 on Neale in all repects and will just scrape 4b's in SAT's.
I stuggle to believe with this SPLD load that he won't be on SENS register.

Can he type? Could his 'fingers' learn the spellings?

Gr8 idea thanx, will try. Did do a dyslexia programme once, which had a component for spellings of typing them out, just clicked why.

If he can't retain all 12, can he retain fewer? Perhaps that's just too many. We sing spellings eg this week ds (yr 2) has unusual so we've been chanting un us ual!