Mikrotik without NAT with "end-to-end" addressing. How?

Question

Computer networks

We have:
Networks X - 10.61.5.0/24 ,
Y - 10.56.0.0/24 and
Z - 10.57.0.0/24.
The gateway for the X network is a device that cannot be replaced by Mikrotik with IP - 10.61.5.1 ,
Mikrotik RouterBOARD 951G 2HnD with IP - 10.61.5.4 - which looks at the gateway 10.61.5.1, which, in turn, looks at the Y and Z networks, and also the
second IP 10.61.5.6 - which looks into the local network X.
How can I make packets go from network X through Mikrotik to networks Y, Z and back without changing the destination/source IP?
UPD: Added a diagram.

And export configuration

/ip firewall filter
add chain=input comment="default configuration" protocol=icmp
add chain=input comment="default configuration" connection-state=established,related
add action=drop chain=input comment="default configuration" in-interface=ether1-gateway
add action=fasttrack-connection chain=forward comment="default configuration" connection-state=established,related
add chain=forward comment="default configuration" connection-state=established,related
add action=drop chain=forward comment="default configuration" connection-state=invalid
add action=drop chain=forward comment="default configuration" connection-nat-state=!dstnat connection-state=new in-interface=ether1-gateway

/ip firewall nat
add action=masquerade chain=srcnat comment="default configuration" out-interface=ether1-gateway

/ip route
add distance=1 gateway=10.61.5.1

Answer 1

if 10.61.5.0/24, then how does 10.61.5.1 understand that it is necessary to send packets to the 10.61.5.0/24 network via Mikrotik, and not directly?

Answer 2

1) Allow the necessary chains in the firewall (by default, a lot of things are blocked there).
2) Set up routes.

Answer 3

routing w

Answer 4

Yes, my friend, you are a noble masochist, then you will get confused in these shit when an accident happens.
Bring Mikrotik and connected devices to another subnet, set the gateway to 10.61.5.1.

Answer 5

And if you combine two ports into a bridge and tell the bridge to work in dumb switch mode....