Question : Problem: PPP Multilink with RIP configuration help

I was wondering if someone could help me with a PPP Multilink configuration utilizing two T1s and RIP.

Ive been asked to add a second point-to-point T1 between two offices.  They currently have one T1 but it is being heavily utilized so they want a second link and they want them load balanced.  Ive found docs on Ciscos site to configure PPP Multilink and it seems straight forward but the offices are also utilizing RIP.  Each office has about 30 servers and 100+ users.  Having both offices in the same subnet and utilizing RIP is definitely not the best configuration but I was asked not to change it.

Both offices are in a 255.255.224.0 subnet.  Both offices obviously use their local router IP as their gateway address.  The serial interface on both routers doesnt have a specific IP address.  It is using the IP of the Ethernet port ip unnumbered FastEthernet0/0

Is there a way I can add a second T1 and configure PPP Multilink without changing the IP address of the Ethernet port?  I dont want to have to change the gateway IP on all the servers and other equipment at both offices.  Any configuration help / advice would be greatly appreciated.

Answer : Problem: PPP Multilink with RIP configuration help

Here is an example config:

int s0/0/0
no ip address
encap ppp
ppp multilink group 1

int s0/1/0
no ip address
encap ppp
ppp multilink group 1

interface Multilink1
 ip unnumbered Fastethernet0/0
 ppp multilink
 ppp multilink group 1

Do this on both sides of the T1's.  Basically, you are using the multilink interface as the layer3 interface instead of the serial.  The RIP config shouldn't need to change.