"The issue is that the Debit Depr and Credit Accum Depreciation was never done."
Get the tax forms and catch up the bookkeeping. Date it correctly for the reporting.
"are you saying that you are creating sub-asset accounts and not hitting an expense account with the Depreciation Expense at all?"
No. You provide Cost. You cannot enter Depreciation without offsetting that to Expense, but historically, it is Retained Earnings, now. All historic expense is in Equity, now. If you are catching up the entries with Historic dates, it is expense; if Now, it is Prior Equity = Retained Earnings. It depends on what you are entering: historic data or Missing data.
"How would you do that - Debit sub-asset acct Depreciation and Credit Accum Depreciation?"
I don't know if you are asking about the Missing info or the sale; I don't know if you just described 2 fixed asset accounts, because those are only Names. Sorry.