i'm not sure how this works because the second Obitalk number is not assigned a default gateway. But I have this setup and it does work. If it doesn't work for you let me know and I will find a solution. I have my suspisions.
sign up for a second Obitalk account and get another Obitalk number for the second pc. You don't need to add a device to the account and you don't have to use a gmail address.
Set up the Obion on the second pc using the new Obitalk number. (you will have to uninstall the Obion app; and reinstall using the new username and password)
Do you want to use the same service for outgoing calls for both pc's, or maybe 2 different google voice accounts set up on your Obi.
If you already had the Obi as the default gateway for the first Obitalk number your
Obitalk Service > InboundCallRoute might look like this
{(290xxxxxx)>(xx.):SP1},{(290xxxxxx):aa},{ph}
add the second Obitalk number to the route like this
{(290aaaaaa)>(xx.):SP1},{(290bbbbbb)>(xx.):SPX},{(290aaaaaa|290bbbbbb):aa},{ph}
Set the SPX for whatever service you want to use for calls from the second pc - sp1 or sp2 (or li if you have service on the LINE)
Both Obitalk numbers will act the same, and you can direct dial from both using 10 digits. If you call the number for the Obi itself your calls will be answered by the auto attendant. Actually you can just dial # to reach the attendant.
I didn't test speed dial, but I guess both will act the same for that also.
And you can call her laptop from your pc by dialing **9 + her 9 digit Obitalk number
outgoing calls from your pc will carry the caller id of the service used from the Obi. So if you set up 2 google voice accounts and set pc #2 to use sp2, both pc's will have their own google voice number used for their respective caller ids.
you could do the route like this if they both use the same service
{(290212910|290175780)>(xx.):SP1},{(290212910|290175780):aa},{ph}
I just separated the two numbers to make it easier to set them for different providers, now or later.