comma before 'and' between dependent clauses [conjunction]

[Wernazuma]

I know that, according to the rules, a conjunction of two independent clauses is preceded by a comma.

But what happens if a subordinate part of a sentence is itself divided by two independent ones?

"As they were sick[,] and the doctor wanted them to stay in bed, they could not make the trip."

I would argue that in such a case, no comma is to be placed since the subordinate part is a unit of meaning.

Thanks.

 

[Old Novice]

It has been many years since I've studied grammar, but I would not put the comma in unless I repeated the "as" or used an alternative:

As they were sick, and as/since the doctor ...

Without a comma, I would understand the "as" to apply to both clauses. Conversely, with the comma but without the repetition of the "as", I'd be a bit confused as to how the second clause related to the rest of the sentence.