The Vacker Portraits were revealed to exist in Flashback. They are stationed in the reception hall of Everglen, where the Vacker family holds Winnowing Galas. Single portraits along with a full family portrait were painted.
Della Vacker had them painted a few months after Alden's mind was healed by Sophie and before they knew Alvar was part of the Neverseen, saying that they needed to commemorate that they were still together.
“My mom said we needed to commemorate that we were all still together. Aaaaaand then we found out about Alvar.”