yes i think that is peerfectly fine…. its ur special day i think that you shoudl be able to ask one little favor from them!!!!

I would suggest “cocktail attire” if the wedding is in the evening. Semi-formal is a lot of different things to different people, and cocktail attire is a step below formal, which is really what semi-formal is. Since you cannot force people who aren’t Filipino to dress in that manner, I’d suggest saying something about “Festive Filipino and Cocktail Attire”. I’m not really sure. Usually the people at the invitation places know the etiquette for things like this. I’d ask them when you go to order.

It’s perfectly appropriate, indeed it”s a kindness, to give people some idea what kind of thing to wear – nothing’s more embarrassing than turning up in jeans when everyone else is in black tie, and vice versa. But be clear (e.g. “semi-formal” means different things to different people) and give them options. It would be unreasonable to insist on just one form of dress which would mean that all your guests who didn’t own a tuxedo/a sarong/white tie/whatever would have to buy or hire it.

Proper attire is often addressed in a wedding invitation. Since you have so many stipulations, you mite want to include a short note requesting the above.