Seeing as or seen as? Or neither?

[BroccoliSpears]

... and seeing as everybody wanted another drink we opened some more wine.

Or

... and seen as everybody wanted another drink we opened some more wine.

the former

seeing

Seeing

seeing as

although it's really a present-tense-only thing:

'Seeing as everyone's still thirsty I'll open some more wine!'

I knew it!

Thank you!

Smug satisfaction of being right.

And yes, you're right too Mrs B - I spent ages trying to mash my brain to come up with a less clumsy example but I couldn't work out what to change.

Well, I would probably say "since everybody wanted another drink, we opened some more wine" but if I had to it would be "seeing"

seen as just sounds wrong

Since. Or just plain as.

As