How to Combine 2 Internets of 2 sites wirelessly Bridging together

Hi every one,
I have 2 office sites Distance 1.2 km away with Separate internet in each one, the Site 1 is Main and the 2nd one is Secondary branch of Site 1.
Site 1 have 2 internet connection, 1 ADSL 8Mbps and 1 Wireless TD-LTE, Aggregated Bandwidths with PCC Load balancing method using RB 751-2Hnd.
Adsl link connected to Ether 1 and Wireless TD-LTE connected to Ether 2 and the Lan Side Ether is Ether 5 with IP : 192.168.1.1 .
Site 2 have 1 internet connection. 1 ADSL 8Mbps over normal ADSL wireless modem router with IP 192.168.20.1/24 no Mikrotik router or etc.
Site 1 and 2 Clients Must have the same IP Range 192.168.1.0/24 .
I connect Site 1 and 2 with wireless bridge with 2 RB Metal 5SHPn using Transparent Bridge Networks using MPLS method. and now each sides clients can ping other sides clients .
Now the problem is how to Providing Internet to the second site to the first site to aggregate the bandwidth of all three Internet and share it for users of each of the two sites, so that users of the second site can access the Internet only through the wireless link, and the modem of the second site plays a role in the distribution of the Internet on the second site Not have In general, the goal is to create a central distribution system of the Internet, given the scattered location of Internet services.

My network map is below. Please take a moment to resolve this issue.
Thanx,

https://wiki.mikrotik.com/wiki/Manual:PCC