Rectangle Tablecloths on round tables

Could you do something like this? Use the round white tablecloths as a base and put your colors tablecloth on top? Might need to hem the rectangular tablecloth to use it like this.

To get that look, you would have to have an expert seamstress cut them in half and square them up. The labor costs per tablecloth alone will be more than renting what the venue has available.

If you want them to be perfect, I agree! But if you don't care if it's perfect, you have access to a sewing machine, and you have nothing else better to do (aka me sitting at home cuz spin class, hanging with friends and family, and eating out is still cancelled) then I think it's achievable.

We used rectangular table cloths at the wedding venue I worked at. If they're large enough and you use 2, you can get it to look really nice.

Tucking the ends in is much easier! That's a great idea. Also you probably already thought of this but, is it possible to just return them? Or you could list them for sale on Facebook Marketplace and see if there are any takers.

No pinning needed. We only used round tables but the linen company we did business with only did rectangles? I would do a criss-cross of the squares, make sure they're laid out evenly. Not that you'd know off the top of your head, but ask them the diameter of the tables and compare that with the size of your table cloths. I don't know that I'd do a runner with rounds, but that's completely up to you! I learned some really fancy napkin folds that can look really nice as well.

Did you say they only have white? See if you can get them to do napkins in one of your colors? We always had white and black linens in stock, and we would order special colors if they wanted. It was only ever more expensive if they wanted the really fancy linen (because we had to outsource).