Hi everyone! I could really use some help with this, because I have no idea what I'm doing.
Basically, I'm trying to create a SQL View in ArcCatalog that references four SDE feature classes of various pavement types. They were published as a feature service through ArcGIS Pro to our organization's Portal (e.g. they are hosted on our own servers, but I am not the author of the data) for multiple people to survey in Field Maps. I therefore want the View to be linked in such a way that it automatically "refreshes" to reflect any updates that are made to the parent feature classes.
I was able to create a SQL View through ArcCatalog with the command UNION ALL to grab all records from the parent feature classes. Initially, the total number of records in the View matched the total number of records from all four parent feature classes. However, I noticed today that the View now has 1,241 more records than before. I'm quite sure no one but myself is looking at/making changes to the parent data, and all I've done is delete a single record from one of the parent feature classes to test that updates are translating. So, I'm not sure where this disparity is coming from.
I wonder if I need to "Register with Geodatabase" to get my View to sync up properly. Apparently it needs an OBJECTID field with unique values. Here's where I run into issues; each parent feature class has its own OBJECTID field that starts with 1, so when I run the UNION ALL command on them, the OBJECTID field has duplicate values. How would I go about adding and populating an OBJECTID field with unique and sequential values to my SQL View through ArcCatalog?
Here is what I have so far:

The highlighted items in the Catalog tree are the four parent feature classes. The first portion of the View Definition seemingly works, but I'm struggling with the last two lines of the command (concerning the new field). How would I adjust my View Definition to add and populate this new unique identifier field?
Any help would be greatly appreciated!
ArcGIS Desktop 10.8.1 - ArcGIS Pro 2.6.1 - Portal for ArcGIS 10.8.1 (production server) - Portal for ArcGIS 10.9.1 (test sever)