If you happen to use Adobe Analytics you are able to track other engines through the Campaign Variable or other eVar. This will allow you to track conversions on these additional engines. In conjunction with this, you could use the data tracked by AMO and the additional eVar (tracking unsupported engines) to help correct any conversion attribution issues. This will not track your engine data (clicks, cost, etc.) but will allow for conversion tracking. Speak with your AMO Account Manager about how to use this data in conjunction with AMO data.