When modifying (adding/removing) fields from the MultiField (by code), I allways have to add/remove the Multifield in the BackOffice in order for it to appear. Is it to possible to update a MultiField by code?
I usually solve it by deleting the MultiField from the Backoffice and then build the solution…or go info the backoffice (manually update)…But it’s a struggle when having multiple environments.
Standard behavior is that templates and fields defined in code are only created/updated during startup if they are new (read more).
You can modify DefinitionSetup.InitFields() to always update fields from code on startup, will require adding a call to _fieldDefinitionService.Update()
I have only tested this with templates myself and not with fields so I hope it works, try it out and post here on how it goes.