What you need to do is to go the /events directory and make a backup of the "1757 Events" text file (just copy and paste in the directory). Then open that file (use a text editor not word) and find the event:
RUS_MemelLanding175
Replace all the text in that event with:
SelectFaction = $RUS
SelectRegion = $Memel
SelectFaction = $RUS
SelectRegion = $Memel
StartEvent = evt_nam_RUS_MemelLanding1757|1|1|NULL|NULL|$Memel|NULL
Conditions
FixedDate = 1757/06/28
Actions
DescEvent = evt_desc_RUS_MemelLanding1757
SelectRegion = $Poniewicz
SelectRegion = $Poniewicz
BlockState = 0
SelectRegion = $Wileia
SelectRegion = $Wileia
BlockState = 0
SelectRegion = $Wierzbolow
SelectRegion = $Wierzbolow
BlockState = 0
SelectRegion = $Wischiten
SelectRegion = $Wischiten
BlockState = 0
SelectRegion = $Lyck
SelectRegion = $Lyck
BlockState = 0
SelectRegion = $Niemen1
SelectRegion = $Niemen1
BlockState = 0
SelectRegion = $Niemen2
SelectRegion = $Niemen2
BlockState = 0
SelectRegion = $Wierzbolow
ChangeRgnOwner = POL;PRU
AddSubFacRgn = RUS;$Wierzbolow
CreateStruc
SetType = $Depot
SetLevel = 2
SetName = Border Depot
Apply
ChangeSupply = 200;50;0
This will sort out the problem of the Russians being blocked in Wierzbolow on arrival. They can now move onto Koenigsberg. Movement from there across the rest of Poland will depend on proper use of the cards that allow you to use light cavalry to increase your military control.