I need advice! Do you recognize these? And what's the best way to sell a collection?

Get bids from the big names and sell it as a lot. If you let someone buy only the good pieces you'll have a whole bunch left that you can't move. Also, prepare her for the low prices she will likely net. Good luck.

They look like Carette based on the under carriage design. They are attractive. There’s a green one on eBay right now. Unfortunately, I don’t think it’s super valuable. Anything Pre-war Marklin commands the highest prices.

George

I'm not much on the identification side, instead if it were me selling these, I'd  use GVDOBLER' advice. Sell as a set, not individually...best of luck as these cars are very nice lookers...

Before trying to sell those, I would clean them and take new photos.  When I see so much dust, I wonder what else is wrong with them.

I wouldn't touch them to be honest.  At best get a soft haired brush and dust it.  The finish on the cars look potentially a little brittle and they may chip while cleaning them.  Sell as a set. 

Thanks guys for the advice.  It's greatly appreciated.