https://www.epo.org/en/service-support/faq/myepo-services/online-filing-software/pct-procedure-and-online-submissions-0

Can I use WIPO's ePCT service to file documents online with the EPO acting as receiving Office?

Yes. For more information on how to use and set up this service please refer to the WIPO website.

As from 1 November 2016, the ePCT service can be used to file subsequently filed documents, as stated in Rule 89bis.2, and file a demand, as stated in Chapter II of the PCT. Payment of fees related to the demand can also be indicated via this method.