I have done a brief search of this enormous forum and the various government websites but not had a clear answer.
I want to apply for uk passports for my two us born children. Do I need to send two copies of my birth certificate and marriage certificate one for each passport or can I just send one of each along with the children's birth certificates?

It's all going in one package, so only one set needed.

As Bob said. Include a covering letter explaining that's what you've done.

Dean

and triple check everything is done correctly before you send - because if one application is wrong - and they have to return something to you - it coud mean eveything comes back together or stuff is seperated from its docs etc causing delays and confusion.

Thanks for your thoughts. It would make sense to not have to send multiple marriage certificates etc. since in the UK at least I think you generally only have one birth and marriage certificate. I was going to use the post office check and send service which costs a bit more but means that you are more or less guaranteed to not have it sent back. Next problem is how to get my 7month old to sit still for a passport photo..

make sure you use the credit card from to pay if you can - because that allows them some leeway if the price changes after you send it in. Otherwise if you send a money order or something for a specific amount- and it changes - it can cause delays while that is sorted. Additionally - once the payment has gone through - you are able to get a much better idea of when yours will be processed - something you dont know with the money order option - so it makes it a lot harder to chase up if it seems to be taking a long time.