You will be able to upload these conversion through the AdWords API and associate the clicks with the conversions. Please check
this part of the guide for more information. Once you create the
UploadConversion object, you need to associate the offline conversions by passing the GCLID, conversion time(with
timezone ID), conversion name, and optionally the conversion value and conversion currency to
OfflineConversionFeedService. You can also check out the
validation rules and
tips which might be helpful. Code samples in Java can be found
here as a reference. You can find the code samples in other languages
here.
Let me know if you have any other questions.