Refreshing one language while learning two others. Bad idea? | General discussion | Forum

I'll start with a bit of backstory before geting back to the big question.

My parents immigrated to Canada from the Netherlands some years before I was born.  I grew up in a bilingual household and, up till a few years ago, considered myself fully fluent in both English and Dutch.  Hell, Dutch was my first language.  I really let my Dutch slip over the years and would simply rate myself as "generally proficient" at this point, and will admit to speaking some sort of "Neder-Engels" on occasion.

In the meantime, I'm learning Spanish for work and Esperanto for fun.  I honestly wasn't planning to learn both at once but as we all know, life likes to jerk you around every now and then.  Most of the time they don't interfere with each other but some days it takes a great deal of mental fortitude to keep them from merging into what I will henceforth call "Eserpañol".

I'm trying to figure out whether bringing my Dutch back up to fluency would screw up my other language efforts or whether that mental division still exists and I'm worrying about nothing.  I'm going to give it a shot either way but I'd love some opinions before taking the plunge.  Do you think trying to refresh my Dutch would interfere with learning Spanish and Esperanto?  Please let me know what you think, good or bad.