Hi Marion,
I believe your primary question of how to automatically establish the relationship on both the Collection Object and Container sides at once can be easily resolved, however this would not require a Collection Relationship. Moreover, Containers are not technically supported in Specify 7, and we instead recommend utilizing Collection Object Groups.
Please review the information below, consider the follow-up questions, and let us know if there is anything else we can do to support you in this area!
Simplifying Workflow As-Is
Foremost, I believe we can reduce the steps in the workflow described below by using the features available for the Collection Object (CO) subview, as an Independent Subview on the Container forms.
If I use the “Collection Relationship” feature, I have to manually create all the collections for the 5 eggs, which is 20 operations.
Because CO on your Container form is an Independent Subview, the 
and 
icons to the right of the header are available for finding and adding existing records () or creating and adding new records () to the Container record. Thus, associating COs with a Container can be done from the Container itself, rather than going to each CO record.
Collection Object Groups (COGs)
COGs were created to supplement the lack of container support while carrying out the GeoSpecify extension. They are documented here on the forum, with more resources about their use coming soon. I believe this could supplement your need for Containers and ensure long-term support for the database workflow.
Similar to Containers, you can create a COG, set a Type, and add CO records in the independent subview. The COG would then represent the clutch, and each CO an egg. The relationships still exist for each CO added, which can be viewed from the COG by editing the fields shown in the subview.
Collection Relationship
We expect that a CO Collection Relationship is established between two collections (although they can exist in just one) and is then added to, and works between, the Collection Object forms on each side; paying respect to which collection’s COs are the ‘source’/left and which are the ‘destination’/right.
A CO form on the source side has the one-to-many view as shown in your screenshot. This in a way, acts sort of like a Container or COG without the ability to deem a type or add remarks. On the destination side, the CO form simply includes a link to the related source CO, serving as a one-to-one from this side.
Destination CO example:
Thus, supposing that Containers are supported in Sp7, this table still does not directly interact with collection relationships. Rather, a Container record could be associated with COs that have a CO relationship.
Will you please clarify what we are missing about your workflow in this regard? How do you expect a Container or COG to function and/or interact with the Collection Object Relationship?
– Bronwyn
