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Compare and merge

Copying a project is how you explore an alternative without risk; comparing is how you get the good parts of that exploration back. The Compare / Merge tool diffs two projects that describe the same site, shows every input difference — facilities, criteria, relationship groups, relationship edits, to-dos — and applies the changes you select into a recipient project. It closes the loop that Copy opens: copy, experiment, compare, merge back what worked. For the click-by-click flow, see Comparing and merging projects.

Learning objectives

By the end of this lesson you should be able to:

  • Pick the right source and recipient for a merge
  • Read the comparison sections and their add / update / only-in-recipient rows
  • Predict which differences the tool will and will not surface
  • Apply a partial merge safely, keeping deletions explicit

Direction matters: source → recipient​

A comparison always has a source and a recipient, and selected changes flow one way: into the recipient. The same two projects produce mirror-image readings depending on direction — a facility added in your working copy reads as an addition when the copy is the source, and as an only-in-recipient row when the direction is swapped. Before selecting anything, check the banner and ask: which project should end up changed? That one is the recipient. Use the swap button if it's backwards.

What the comparison covers​

The tool compares the project's inputs, grouped into five sections:

SectionWhat's diffed
FacilitiesAdded/removed facilities and per-field updates: name, notes, layer, front side, shape, categories, attributes, explosives
Project CriteriaCriteria standards present in one project but not the other
Relationship GroupsGroups added/removed, priorities, matrix values, and facility assignments
User Relationship EditsManually overridden relationships and barricade links
To-do ItemsAdded, changed, and recipient-only to-do items

Everything else — analysis results, build-generated relationships, drawings, project settings, users and sharing — is out of scope by design. A merge changes what you put into a project, never what Siter calculated from it; re-run analysis (and rebuild relationships, which Siter offers when relevant) after merging.

How facilities are paired​

The tool matches facilities between the projects automatically. Copies carry an exact lineage link, so a copy compared to its source pairs cleanly even after renames and moves. Facilities without lineage are paired by name and shape similarity and flagged with a Likely match badge — review those pairs, and use break match on any that are wrong. A broken pair becomes an addition on one side and an only-in-recipient row on the other.

Deletions are always explicit​

Select All never deletes anything. Rows that exist only in the recipient default to Keep, and each must be switched to Delete individually. The confirmation dialog lists every deletion before the merge runs. Almost everything a merge does can be reversed from the map with Undo — the exception is to-do changes, which the dialog calls out.

When compare/merge beats the alternatives​

  • Copy experiments — merge a successful what-if back into the baseline instead of redoing the edits by hand
  • Parallel edits — two people worked in separate copies; compare each against the baseline and merge selectively
  • Reviewing a copy's drift — even with no intent to merge, the comparison is a readable change list of everything a copy has diverged from its source

For moving a whole project between environments, export and import remains the right tool — compare/merge moves differences, not projects.

Try it​

  1. Copy a project you can experiment in (see Copy)
  2. In the copy: rename a facility, move one, change an explosive weight, add a facility, and delete another
  3. From the Project Management page, select the copy and the source and click Compare / Merge
  4. Make the copy the source and read each section — find your five edits, then expand the added facility's preview and open the shape-change panel for the move
  5. Select everything except the deletion, set the deleted facility's row to Keep, and merge
  6. Confirm the source project gained your edits but still has the facility you deleted from the copy — then undo the merge from the map