I think you are making this more difficult than it needs to be.
If I understood your original post, you only have two service providers: Anveo and Google Voice. You formerly had one SP pointed to the Phone 1 port, and the other SP pointed to the Phone 2 port. What drgeoff pointed out, is that you now essentially have a OBi 200. It still can host up to four SP's (SP1--SP4). The only significant difference is that you only have one physical phone port, which will work on one analog telephone via the one working RJ-11 jack.
Just choose: which of the two service providers do you use the most for outbound calling? Configure SP1 to use that service. Configure SP2 to use the other service. Inbound calls from either service can ring the one working phone line. This is very easy to set up using the OBiTALK dashboard. I don't see any point to forwarding from Anveo to Google Voice or Google Voice to Anveo, unless you want to divert inbound calls through Anveo to pick up caller ID name (CNAM).
For example: Assume you make the large majority of outbound calls via Google Voice. Configure SP1 to use Google Voice. Configure SP2 to use Anveo. When you want to make an outbound call via Anveo, preface the dial string with **2. That's all you need to do, other than to set both SPs to ring the Phone 1 port, not the dead Phone 2 port.