[mythtv-users] Updating the end time or offset of a recording in progress

[mythtv]

I'm trying to create my own version of Myth Recording Extender but using 
the Dvr services API instead of directly writing to the DB. I'm able to 
call the GetEncoderList service and determine that an NHL game is being 
recorded, I can get the status of the game from a website. I can get the 
original recording rule that caused the game to be recorded.

What I can't do is to actually extend the recording. I can call 
UpdateRecordSchedule and pass it a new endTime (which only seems to 
actually work once), or I can give it a new endOffset which seems to 
work multiple times. But I think I have a problem: The recording rule is 
actually a Power Search and I'm not sure it's actually affecting the 
in-progress recording. When I get the rule from GetRecordSchedule, the 
actual start and end times are from back when I created the rule (back 
in 2015), so I don't think I'm really getting the right rule.

Is there some way within the services to extended an in-progress recording?

Thanks for any help.