That does sound tricky. Maybe you could consider them to be sub-events

• https://schema.org/Event
• https://schema.org/superEvent
• https://schema.org/subEvents

... but I am unsure as to whether subEvents can have specified dates (start / end)

I might look more to something like EventSeries

• https://schema.org/EventSeries

"An EventSeries is a collection of events that share some unifying characteristic. For example, "The Olympic Games" is a series, which is repeated regularly. The "2012 London Olympics" can be presented both as an Event in the series "Olympic Games", and as an EventSeries that included a number of sporting competitions as Events.

The nature of the association between the events in an EventSeries can vary, but typical examples could include a thematic event series (e.g. topical meetups or classes), or a series of regular events that share a location, attendee group and/or organizers."

This would seem to be a better schema to use in your situation.

This is the JSON-LD example of implementation from Schema.org:

• https://d.pr/f/WDYKni.txt (TXT file)

It looks like it could be re-engineered to do what you want

Whilst Google don't explicitly state that they support EventSeries yet, IMO their documentation cycle for what they do support is wildly out of whack. I have seen front-end instances of them experimenting with loads of schema that isn't in their official documentation. As such I wouldn't be overly, dramatically bothered by that. At the end of the day, the home of schema is Schema.org. I actually often push for schema which Google don't explicitly state that they cover, and I'm often pleasantly surprised

It doesn't always yield fancy rich-snippets, but it does help Google to gain contextual awareness and rank pages more appropriately. In fact you can read about that here: https://www.searchenginejournal.com/google-follow-our-structured-data-requirements-to-ensure-rich-result-eligibility/329679/

"Independently, you’re always welcome to use structured data to provide better machine readable context for your pages. Which may not always result in visible changes, but can still help our systems to show your pages for relevant queries."

1.) It depends on Google's perception of what has happened, you may or may not get those rankings back (ever)

i. If Google applied 'active' ranking reductions (usually signified by a penalty message in Google Search Console) then the disavow work alone wouldn't work, you'd also need to submit a reconsideration request. For a recon request to go through, especially a links one, it ranges from 2 weeks to 4 months for them to even respond to it (the higher range is usually for repeat offenders)

ii. If Google applied active ranking reductions without serving you a penalty notice, the disavow on its own should be processed relatively quickly and rankings should begin returning a week or two after the disavow is processed. Note that this is the rarest circumstance, Google almost never apply active ranking reductions without also sending a penalty notification

iii. If Google didn't apply any active ranking reductions, it simply means that links which used to count - no longer pass SEO authority. Doing a disavow doesn't magically bring the authority back (so in this situation you don't see ranking gains from disavow work, this would be called an algorithmic devaluation - not a penalty)

Items (i) and (iii) are infinitely more commonplace than (ii), which is extremely rare

2.) Build good links to replace the crappy ones you have lost