Static on chiffon

A couple of suggestions from t’internet,
rub talc on your legs

Rub a dryer sheet over the trousers (on the inside)

And you’ll love this last one

Unbend a wire coat hanger, put trousers on and carefully rub the wire all over your legs, being careful not to snag the trousers . I’d like to see that being done.

Maw my top is quite long. I haven't tried moisturiser. I will give that a go

I read somewhere that you can stop man-made fabric clinging to tights by rubbing a tumble drier sheet down the tights. I have never tried it so can mot verify.

Have you tried rubbing moisturiser onto your legs?

I believe you can get special 'petticoats' for under trousers. Just googled them and on Amazon they are called pant liner slips. I hope they solve the problem for you.

I believe you can buy “trouser slips” I.e.undertrousers, which may be anti static. Worth googling.
Are you bare legged under the trousers?
Cotton pants of course.
What stops them being see through? (Trousers I mean)