how to correctly link dropdown lists

I am currently working on a pdf form on acrobat pro for work and I ran into some trouble when attempting to add script when there was already script made. I am very new to this so these struggles might be due to that.

I had to create a new dropdown list (List B) on an existing form and link it to another list (list D). (I successfully accomplished this) However, There is another drop down list (List A) that is also linked to List D and now the link will only work at the start but will quickly go away and stick to my new changes.

Essentially, when i choose "yes" in (List A) i need it to link to (List D) without (List B) effecting it.

This probably made no sense at all but if anyone knows how to fix this that would be great!