I am in need of a routing solution to link my three topologies

[IsaacNP]

I am stuck trying to figure out how I can link my 3 topologies together without changing it too much and breaking the connections.
Such that my Main topology's PCs can still ping each other successfully.
Such that my Multilayer topology's ISP and PCs can ping each other successfully.
And that my ASA topology's PCs, server and router can ping each other successfully.

The IDEAL solution is that my PCs on the Main Topology can ping the Multilayer's Topology successfully. However, and I may be wrong on this one, that PCs on my Main Topology will be unable to ping PC6 and 7 because of ASA5505 security level 100 but should be able to ping the server 8.8.8.8 and ISP2 8.8.8.1. On the other hand, PCs 6 and 7 I think should be able to ping PCs on the main and multilayer's topology successfully. (I would also need the configuration details(steps) and brief explanation as i need to log it down in my worksheet).
Any other solution is acceptable as long as my Main Topology can connect to other 2 topologies.
.pka file is attached

[Georg Pauwen]

Hello,

at first glance, it looks like a major reconfiguration project, the main problem being that the routers you currently have in your topology only support two interfaces, and you need three. The 4331 routers support three interfaces, but that would mean reconfiguring all the connections. Is that in the scope of your project ?

[IsaacNP]

Hello,
I am unable to touch R1, R2(I have to use 2901 routers) and the PCs and switches A, B, D, and E as it is the topology my teacher requires me to set up. I also can't change the addresses of my main topology as this is an assignment to put my understanding of PT 11.7.5 to the test. 

Which is the first part of my assignment, the second part is adding 5 extra features to my main topology (this task requires me to play around with things I havent yet learn about packet tracer), but I have to be able to still ping my PCs on the main topology.

[MHM Cisco World]

OSPF with
net 0.0.0.0 0.0.0.0 area 0 <<- this simple and easy routing protocol config for lab.

[IsaacNP]

Yes I would have used an OSPF for this assignment (on my main topology) but my teacher wants me to use IP route for it so i have no choice but to. I did OSPF on my ASA topology (the ASA and Multilayer switching topology are the only ones I can edit in this assignment, they are for the second part of the assignment (I am free to do whatever I want for it as long as there are 5 extra features that adds to the main topology and doesn't hinder the pinging success of my PCs in the main topology which is why I am trying to combine them).