Nat and flow redirect

[ghost <cu34_(_at_)_m1_(_dot_)_is_(_dot_)_net_(_dot_)_tw>]

hi:
  i have a local lan,i want to separate it become two,
A is Office lan,B is work lan.

  I know I must use vlan to set it,
or the MS netbios will still let the two lan can see each other.

  but the question i think is:

  1.if the office lan and the work lan all use 192.168.1.x
    ->office : 192.168.1.224~255
    ->work   : 192.168.1.1~64
    i want to let the two lan use the same openbsd box link to internet
    but use the different ip to d the gateway, 
    office nat ip : 192.168.1.254
    work nat ip   : 192.168.1.1
  2.i have two adsl,but i have no l3 switch,
    so i use the ip "y" in adsl1 to do the nat ip -> 123.45.67.89
    but if the flow is want to go to a ip which is in adsl2
    (ex:124.46.68.81),
    i can redirect it from ip "y" to ip "z" in adsl2,
    Don't need route adsl1 -> internet -> adsl2
    (i can set a ip "w" in adsl2 on the openbsd box -> 124.46.68.80
    to do the nat ip for adsl2)

  If someone can help me or where I can find the information
  to learn about that?
  
  thank you : )

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