Use of the subjunctive

Use of the subjunctive
 

From a novel I'm reading (written in Spanish by a Spanish speaker).

"Porque él así jugaba, cuando el muerto era suyo o le parecía benéfica su desaparición, mandaba enormes coronas de flores, tan enormes que no cupieran por la puerta de la casa en que se velaba al difunto."

I'm wondering about the use of the subjunctive "cupieran". Is it obligatory here, or does it have something to do with the perception of the narrator. To me, it appears to be a statement of fact, that the wreaths wouldn't fit through the doorways, so I can't see why the indicative isn't used. Am I missing something obvious?

Thanks

There's a slight difference.
He would send such huge wreaths they couldn't fit through the door OR
He would send such huge wreaths they wouldn't fit through the door.

Mandaba coronas de flores tan enormes que no cabían por la puerta OR
Mandaba coronas de flores tan enormes que no cupieran por la puerta.

I understand that the fact the wreaths couldn't fit was accidental in the first sentence.
In the second sentence it's definitely intentional, i.e. he goes out of his way to make sure that the wreaths won't fit, which follows, as it starts by saying that he liked to play that way.

(nothing)

I agree with Ambarina. :)

Perdón, ese "cabían", ¿no debiera ser "cabrían" para ser accidental?

Supongo que te refieres a condicional. Yo también usaría el imperfecto. :)

¿y cuál es el imperfecto?

Cabían.

Thank you PJT.

First time in years I ask a question about grammar, because it caught my interest.