How Alma prefers to handle bound-withs, and the way they transformed those records as part of the migration, is a knotty subject documented across the web both by Ex Libris and institutions and consortia who have migrated to Alma. Note that we are almost entirely concerned here with unrelated titles and items bound or physically connected together in whatever way. We are not concerned with bound runs of periodicals or other series.
Situation in Sierra and many other catalogs
For bound-with materials, most of us are familiar with a system where multiple bib records are linked to each other through 773 or 774 fields and/or each bib is also linked to a single item record. in Sierra, holding records were generally not used for monographic materials so the bib records were linked directly to the item.
Alma doesn't allow multiple bib records to be linked to a single item. During the migration, we pre-identified all of our bound-with items. For each set of bound-with titles, Ex Libris auto-generated a new parent record, mostly blank, but with a 245 of "Host bibliographic record for boundwith item barcode [barcode number]". Then created the 774 fields from the related bib records into this new host record, and moved the item (with a newly created holding record) this new record. The bib records are only linked through the 774 fields.
For Ex Libris documentation on the process, see:
(Note: Millennium is the practical equivalent of Sierra in their documentation)
What to do
Many institutions choose to make changes to the bound-with host records created by Ex Libris during migration.
Within NYARC, we can all determine what's best for our individual libraries since it doesn't seem like our choices in this regard will affect the other libraries (though we're not 100% certain of this, it at least concerns only a very very small portion of our catalog: titles where one library's copy is bound-with other titles while another library owns a free standing copy of that title).
MoMA has not implemented changes yet, but is inclined towards those taken by the CARLI consortium and outlined here:
Other documentation on remediation choices can be found:
Ex Libris notes on 774 $$9 usage here:
MoMA's preferred practice:
The basic steps (not necessarily in a particular order) are:
In the host record:
Change the existing 245 "Host bibliographic record for..." to a 246
Add a new 245 with improved wording.
In each 774 field replace the "$$9 ExL" with a "$$9 unrelated"
Suppress the host bibliographic record
In each related bib record
Further explanation of these steps and the reasoning behind them are covered on MoMA's ALRC wiki pages.