Moving my own WABA's numbers off Twilio to Cloud API direct — is the credit line the real blocker?

Setup:

- I own the WABAs. They live in MY Meta Business Portfolio.
- Twilio is listed ONLY as a partner, with a shared credit line attached to the WABAs.
- I already have my own Meta Tech Provider app, system user, and token with whatsapp_business_messaging + whatsapp_business_management.
- 2 phone numbers, currently live as Twilio WhatsApp senders.

What does NOT apply to me (please don't suggest these):

- I'm not moving to another BSP, so BSP-to-BSP migration is irrelevant.
- I have no SIM access for these numbers, so anything requiring request_code / verify_code is off the table.
- Since the WABA isn't changing, I don't think Embedded Signup is involved at all.

My assumption is that because the WABA stays the same and the numbers are already verified in it, I only need to re-register them against my own app — no re-verification, no new WABA. Please tell me if that's wrong.

Plan:

0. Disable 2FA on the numbers in WhatsApp Manager.

1. Delete the WhatsApp senders in the Twilio Console.

2. Get Twilio's credit line detached, attach my own payment method to the WABA.

3. POST /{WABA_ID}/subscribed_apps with my system user token.

4. POST /{PHONE_NUMBER_ID}/register with my own PIN.

5. Send a test message + confirm inbound webhook.

6. Only then remove Twilio as a partner.

Questions:

1. Does deleting the sender in the Twilio Console automatically detach Twilio's shared credit line from the WABA? Meta's docs say only the credit line owner can revoke it, which would mean I need Twilio to do it via API. Has anyone actually done this and seen which one is true?

2. Meta's docs warn that if you remove the partner from Business Settings before the credit line is revoked, all messaging on the WABA gets blocked. Can anyone confirm this from experience, and how long you were stuck?

3. Once Twilio's credit line is off, can I just attach my own card to the WABA in WhatsApp Manager? Or does Meta force the WABA currency migration path (which clones into a new WABA)? A new WABA would be fatal for me since I can't do SMS verification.

4. Does deleting the sender leave the number's code_verification_status as VERIFIED in the WABA, or does it reset? If it resets I'm stuck, because I can't receive a verification code.

Has anyone done this exact move — own WABA, off a BSP, straight to Cloud API, without SIM access? Any war stories appreciated.