Merge 2 TV Mini-Series and their episodes

Hi,

After a careful check, I noticed that 2 IMDb pages talk about the same TV Mini-Series:

https://www.imdb.com/title/tt39694103

https://www.imdb.com/title/tt41908821

These pages refer to the exact same 4-part documentary series produced by Windfall Films. The double naming is due to the split international distribution between CNN for US (as "Disaster: The Chernobyl Meltdown") and National Geographic for UK/Global (as "Chernobyl: Inside the Meltdown"). I joined evidence in my contributions.

I chose to keep the oldest IMDb page and merge tt41908821 into the older target page tt39694103.

I created 4 contributions for the 4 episodes (1 per episode) and a contribution for the root page. I do not understand why some contributions validate the merging and some not (each of the 5 pages have to be merged). 

These ones are okay to merge:

https://contribute.imdb.com/contribution/261109-140158-442000

https://contribute.imdb.com/contribution/261109-130748-828000

These ones are not:

https://contribute.imdb.com/contribution/261109-131331-001000

https://contribute.imdb.com/contribution/261109-135153-187000

https://contribute.imdb.com/contribution/261109-135424-476000

Can you please make sure all 5 pages will be merged and in the proper order (root page vs episodes, which one first?)?

Thanks for your help
Best regards