I would like to request some terminology assistance - specifically, I would like assistance determining Changeling terminology referring to specific connections between Ponies and Changelings, connections that would not be covered under pony-normal terms (parent/child, brother/sister, husband/wife, etc).

As an example, I have two specific terms, derived from insects, for two of these.
A Changeling who was raised among Ponies, and who therefore identifies as a Pony, is termed an Ariet - derived from the scientific name of the wasp beetle, a beetle species which mimics wasps.
A Pony who is raised in a Changeling nest, whether as the Pony child of a Changeling, or because they were kidnapped/rescued at a young age, is an Alcon - derived from the common name of the Mountain Alcon Blue, a butterfly species which explicitly tricks ants into raising its young for it.

There are (at least) two more relationship roles, however, that I need an explicit term for. In the case of these two, it's a particular cross-linked relationship - a proper relationship of this type must have both parts. This is for a relationship which mimics the ant-aphid relationship in the real world - effectively, it's a pairing between a Changeling, who serves as guardian or caretaker, and a Pony, who serves as a willing love source for the Changeling to draw from. Such a relationship can be, but is not necessarily mutually exclusive - a single Changeling may be watch over multiple Ponies, or a single Pony may feed multiple Changelings.

I would like to request assistance in coming up with terms for both parts of such a relationship; terminology derived in some way from insects is preferred.

Does anyone have any suggestions?

Call the horse an aphid then.

imo, I don't particularly like using bug names for changeling stuff. I was a little irked when Thorax was named Thorax. Not to say that I don't enjoy stories that use them. Honestly, it's all about how the vocabulary is used. Like your word Ariet, right? What if it was used as a derogatory term? Huh? Or maybe at least come up with another word for that purpose. Really, it's all about how it's used. Also, explaining that kind of thing will be difficult. Make sure you have a clueless character who gets to ask such questions, for exposition.