Now silverplate is NOT my thing - so my knowledge is very limited. But I will try to put information that I have regarding the marks. The information is not acurate but to the best of my knowledge. as they all are silverplate - they are sopposed to be silver look alike marks.
I my country I remember from when I was a child in the 60ties. "When you bye 3 towered silver you buy for yourself, your children and their children... when you buy 2 towered silver you buy silver for yourself and your childred.." giving the impression that 2 towered silver was some form of silver....
My plated silver is not polished or clean - it is just something that I from time time hapens to buy - by mistake or when i buy bulk. So these items are from 30 years to approx 100 years - I dont know but...

The Torchmark FDG (Fællesrepresentationen for Danske Guldsmede)
Under G.T. for ??
Mark is from a piece from 40ties to 60ties dont realy know but in that period.
The mark was used from the beginning of 1930ies as a quality mark for silverpladed. Mark was used by various manufactures.
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