One question about RIPE

Hello,

We have a customer that has got a range of IP addresses from one Provider
(say X) and he now would like to use these addresses via our network.

Our sales representatives say it is possible to do
it
1) If Provider X is OK
2) If we have got the agreement from RIPE

Is it correct ?

Would you know which RIPE's form would be used then?

Thanks

Andreas