In ArcMap 10.4 I'm trying to manually join two nearby points on a one-by one basis by visually inspecting a single point in one layer, and associating it somehow with a point in another layer. Using nearby points is troublesome, because I need to use subjective criteria to make that join. For example, I have a geolocated electricty service account point, and I need to associate it with a gas service account. They are not always the two closest points on a map, so I must use my judgement to join them together. The last step would be to join those points to a building footprint which is a geolocated polygon. I'm not savvy in python, so a way to click one point and then click a second point and join them would be something I initially think would be a user-friendly solution?
The standard database way to do this would be to assign each layer--electric, gas, building--unique identifiers, then use the Attribute Transfer tool to point and click and transfer the attributes from layer to layer.
For example, your electric layer could have the following fields: Id, GasId, BuildingId. Your gas layer could have the following fields: Id, ElectricId, BuildingId. Your building layer could have the following fields: Id, ElectricId, GasId.
So, if you want to be able to relate all 3 layers to each other, you would populate these Id's accordingly. Then you would set up relationship classes so you don't have to keep relating them over and over manually. For each layer, it's Id would be it's primary key, and the other Id's would serve as foreign keys to the other layer's.
Here is the link to the Transfer Attributes tool. Note that it does require an advanced license, although it is definitely one of those things one can program around and simulate with a lesser license with python. http://resources.arcgis.com/en/help/main/10.2/#/Transfer_Attributes/001v0000000s000000/