Filter and reconcile listings from multiple source MLSs sharing a single MLS Grid account using OriginatingSystemName
domain: mlsgrid.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Review the account's Mappings page (app.mlsgrid.com/developer/mappings) to see which MLSs and field mappings are provisioned
Filter every resource query with $filter=OriginatingSystemName eq '<mls>' to scope results to a single source MLS
Combine the OriginatingSystemName filter with ModificationTimestamp gt <watermark> for per-MLS incremental sync watermarks
Store OriginatingSystemName alongside each local listing record so downstream logic (e.g., compliance rules, field availability) can branch per source MLS
Watch MLS Grid's release notes for source MLS migrations, which can change an OriginatingSystemName value or its field mappings without changing the MLS Grid account itself
Known gotchas
OriginatingSystemName values are case-sensitive and typically lowercase — a mismatched case silently returns zero results rather than erroring
Because multiple MLSs can share one MLS Grid account, forgetting the OriginatingSystemName filter on any query mixes listings from unrelated MLSs together
When a source MLS migrates its underlying system (as documented in MLS Grid release notes), field names and even the OriginatingSystemName value itself can change, breaking watermark-based sync logic that assumed static identifiers
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