Filter ComboBox

[JGR]

Grettings to all. I am lost.

I have 3 tbls.
tblBBPno with:
BBPNoID (1 to Many)
ysnAvaliable

tblBBP_HistTrac with:
intBBP_HistTracID(Auto)
intBBP_LineHistID (Many to 1)
BBPNoID (Many to 1)

tblBBP_LineHist
intBBP_LineHistID(Auto)
intFRM_No (Use for work and maintance) (Many to 1)
intRM_No (Used only for work shipping number)
intEventID(Shipped(1),Returned(2))

FrmBBP_LineHist
CmBox (intEventID)
CmBox (intRM_No)(New entries allowed)

FrmBBP_HistTrac
CmBox (BBPNoID)???

If (FrmBBP_LineHist)!intEventID)="Shipped", I need to be
able to pick BBPNoID on any row with ysnAvaliable="Yes"

(FrmBBP_LineHist)!intEventID)="Returned" I need to be able
to limt BBPNoID to tblBBPHistTrac w/ intBBP_LineHistID
and/or intRM_No

Any sugestions welcome.

Thanks
JGR