We are thinking about creating a native CiviCRM extension Someone Else Pays.
In CiviCRM you could use the soft credits (with a new soft credit type) to register another contact pay for an event registration, a membership and in theory any contribution. Our customer Domus Medica is using that at the moment. We encounter some issues though. Some of the issues are possibly bugs but some are also because we think soft credits is originally not meant to cater for this. It was meant to cater for soft credits. So we prefer to create an extension rather than fix a few issues in a hackish way and then finding out we have some more.
At this point in time our thinking would be to:
Domus Medica would like this functionality we have a few questions for all of you out there: