Is it possible to merge contacts from different sources and upload them to GMail? I'd like to merge contacts from different sources -- i.e., imported contacts from phone, from sim card, and from my gmail account -- and upload the ultimate contact on my gmail account.

For instance, I know someone's mail adress using my gmail account, and I import his phone number from the sim card. My goal is to update the contact on the GMail account, in order to have also his phone on internet (it's the perfect backup).

Is it possible ? Is it native or should I use another app ?

I'm using a Galaxy S with Android 2.1, unrooted

Thanks for you're help !
This answer is based on comments from Niall C.

There are 5 phases in the process :


Select each contact, and then link them when relevant. The goal is to have 1 friend = 1 contact.
Export the list (Contact > Menu > More > Import Export > To SD Card), it will work even if you don't have any SD card.
Transfer the file to a computer (the file is quite light, even with GPG keys and user pics)
Open GMail, backup your contact by exporting them
Import the VCF file


And that's all ! Your contacts in GMail have now phone numbers ! Don't worry, GMail merge contacts becase their email adress is already known.

Source : How to move phone contacts to Google?