How to get User_id correctly if there is no user account on the site?

Question

1C-Bitrix

How to get the User_id correctly if the site does not use a personal account and another type of authorization, and pass it to Google Analytics to determine the client's path, and assign it a transaction in the future.
The process uses a site in PHP, CRM - Bitrix24 (Not a box), Google Analytics, GTM.
At the moment, there is the following logic:
1. The client goes to the site, he is assigned a Client_ID, he navigates the site and then performs one of the Lead generation options (CRM form, online chat, callback, etc.).
2. When generating a Lead and transferring it to CRM, data about the client and the Client_ID assigned in this session are transmitted. This Lead may not be transferred to a deal, but only a contact with its ID is created (there is a Client_ID field in the contact data - it is used as a multiple one and if there is a repeated Lead to an existing contact with a different client_id, then a new client_id will be added, and there will already be 2 client_id).
3. Next, this Lead will be transferred to a deal, and we will receive a transaction, and it is necessary to transfer transaction data to Google Analytics using the Measurement Protocol, namely:
- User_id - client ID (which was generated when creating a contact in CRM).
- transaction data, cost, product, and so on.
Now the question is: since in this contact we have 2 client_IDs, they need to be assigned to one User_ID in GA for gluing sessions.
4. As far as I understand, it will not be possible to implement this using the standard GA functionality of the User_ID parameter with a separate view, since client_id is not used as a session identifier here.
5. Therefore, it is necessary to use a custom parameter (Custom Dimension) in GA.
Is this diagram correct or not? And whether the data will stick together with a custom parameter.

Answer 1

1) if authorized - read his id and change it
2) if not authorized - assign a random id and write to the cookie , a
situation may arise when a person received a cookie as unauthorized, and then logged in and he got an id = here you can enter the 3rd flag