From: Madrid, Spain
I don't know about a house rule, but may be you a re referring to an existing optional, at least in WIF. From RAW:
(USSR-Japan compulsory peace) If Japan controls
Vladivostok during the first war between Japan and the USSR, the
Japanese player must agree to a peace if the Soviet player wants one.
Similarly, if the USSR controls 3 or more resources that were
Japanese controlled at the start of Sep/Oct 1939, the Soviet player
must agree to a peace if the Japanese player wants one.
In either case, the new Russo-Japanese border is established by the
hexes each controls. Any pocket of non-coastal hexes wholly
surrounded by hexes controlled by the other major power becomes
controlled by the major power whose hexes surround them.
If a peace is reached, remove all forces now in each other’s territory. Put
them in the nearest hex in whcih they can stack controlled by their major
power or its aligned minors.
If a minor makes peace and is now not at war with anyone, remove all its
land and aircraft units from the game until it is next at war, upon which
all its land and aircraft units are again set up as normal (see 19.4). All of
the minor’s naval units remain under the control of their controlling
major power (British in the case of the Commonwealth).
If you are now a neutral major power, remove any MIL units you have
on the map or on the production circle that have ‘Res’ on their back and
place them in the reserve pool. Remove all your remaining MIL units
from the game until you are next at war (see 4.1.2).