Ann: Demerger of Endeavour Group, page-30

I'd say it depends on the ratio of the split. Technically since it's a 2-for-1 split you could just halve your average purchase cost - that'd be the case if both became the same i.e. right now it's $42.91 - so were both stocks to be worth $21.45 at split.
In that case, if you purchased your WOW shares for $40 per share average - then you could say your WOW and your Endeavour shares were bought for $20 per share each.
We'll have to see what the ratio is, which will likely be announced end of month or start of next month when the event occurs and could only be estimated at this point.