Current BMW Dive Watch suppliers?

[timc]

With my 1973 Hamilton W10 off for a service, I have started looking around at other BMW's. I am out of touch. Who are the current supplies of Dive watches and how do you know they have really been issued?

I ask the latter as the CWC SBS divers on the CWC site, seem to already have been engraved with issue numbers / years and I thought that happed in the stores? So if you can buy them straight from the maker with the issue number and year, how can you tell if those being sold else where have really been issued?

Thanks.

Tim