Would it be possible to add a third option to the Calendar Events Repeat section to select the Last day of the month?"Last Day of the Month" is related to the "Last [Day of Week] of the Month" missing feature.
"Last [Day of Week] of the Month" has been requested at least 4 times.
There are 12 "Last Day of the Month" (the 28th, 29th, 30th, or 31st).
There are 29-30 days per year (the 29th, 30th, & 31st of every month) that are the 4th OR 5th "Last [Day of Week] of the Month".
It has been pointed out that you could set up an Event on the wrong day (but one that Groups.io recognizes correctly) and 'simply announce the Event x days early'. This lame work-around isn't worthy of Groups.io (especially as YahooGroups knows how to do it) - unfortunately it's not on the Groups.io TODO list yet...
OTOH, the work-around does suggest that Groups.io could code:
"Last [Day of Week] of the Month" as 7 days before the "First [Day of Week] of the Month" of the following month.
"Last Day of the Month" as 1 day before the "First Day of the Month" of the following month.
An additional date selection of +/- x days (before or after) another date would handle 'conditional' dates:
e.g. the 1st Tuesday after the 1st Monday of a Month (the 2nd - 8th day of a month, not the 1st)
would be: "First Monday of Month" plus 1 day.