https://ibb.co/NWJvHX4 < link to Taeth's map
@Winddancer Would village 10 "Smoltwaeter - West-march" work as the village from which Sigrid is from. We could leave a note here that it is abandoned after all the residents were killed, and it would make sense for Grimthain's patrol to have taken up the chase as the kidnappers passed north of Helm's Deep, headed East towards the Entwash, and caught them just before they crossed the border between Eastfold and Anorien. Given that Grimthain said the children were buried "along the East-West Road [should have been Great West Road], only half a day’s ride west of the Firien-wood" that would put their mounds near the brown 13 cavalry outpost (the forest on the map at that border being the Firien-wood) and, errrr, the opposite direction from Helm's Deep from Edoras.
@Éolath
ALLACAN EDIT If you prefer, and it would help your role-play, I could edit Grimthain's post to say the children were found
dead near the brown 13, but their bodies were transported back to Westfold and their mounds are actually near the red 1, Sceornbeorg - Westfold (which is also Grimthain's home village) as by then they had learned that the old village was completely abandoned?