Hi welcome to the forum,
Yes, top image; Danish Assay Office Mark or control mark the triple tower castle above waterlines in an oval frame-shape, the two digit number appearing in the wavy water lines below the three towers is an indication of the year of assay. Bottom image right; Warden or Guardian mark Danish Assay office in Copenhagen,
SG conjoined for; S. Groth on duty during 1863-1904.
Bottom image left; maker’s mark initial(s) but not clear to me/ unknown. For more information see;
http://www.925-1000.com/dm_Assay.html
And Danish Maker’s Marks;
http://www.925-1000.com/denmarkA.html
Oel.