help needed (swap pins by nets)

Hello All.

I have a 1500 pins BGA with a lot of swappable IO pins.
All nets are routed from the BGA to outside itself.
All destinations are routed close to the BGA.

The swap is long to do (Show element to find the first pin to identify it (from destination) and swap with the closest clines by following it to the BGA pin).

Then I wrote a little skill routine to be able to select the component ((1) on before.jpg) on which pins will be swapped and then both nets(2) and (3) by extracting pin from them. The it swaps them according to after.jpg

My routine does what I want but the "cosmetic" is problematic:
I took a part of the renref (semi-auto.il") for the popup menu and the stop routine.
I have a lot of difficulties to make it works....
Now on Allegro, after running this command, all others commands have to be finished before calling the next one (error msg: E- Finish current command before starting new command)

What I wish (probably useful for others...):
Select the component.
Select net 1
select net 2
swap pins.
select net 1
select net 2
swap pins and so on until I click "Stop" on the popup menu.

the routine (can probably be enhanced!! sorry for my poor knowledge in Skill ;-):
maybe an Oops can be added, a form too, etc....
A lot of things (like variables = nil or something like are there because of many tries to improve it)

----BEGIN----
axlCmdRegister( "swapn" 'Swap_Pin_byNets ?cmdType "Interactive")
defun(swapn_stop ()

   ; Stop the select function  
   ; ########################
   axlClearSelSet()
   axlCancelEnterFun()
   refdes=nil
   net1=1
   net2=2
   num1=nil
   num2=nil
   lengthnum=nil
   lpin1=nil
   lpin2=nil
   pin=nil
   pin1loc=nil
   pin2loc=nil
   Finished=t

);defun stop
defun(Swap_Pin_byNets ()
   axlCancelEnterFun()
Finished=nil
   refdes=nil
   net1=nil
   net2=nil
   num1=nil
   num2=nil
   lengthnum=nil
   lpin1=nil
   lpin2=nil
   pin=nil
   pin1loc=nil
   pin2loc=nil

swapn_Popup=axlUIPopupDefine(nil
            list(
            list("Stop" 'swapn_stop)))

while(Finished == nil
axlUIPopupSet(swapn_Popup)
;-----------------------------Component Selection----------------------------
if(refdes == nil then
  comp=nil
  while(comp == nil
  print("Selectionner le composant dont les pins seront swappees: ")
  axlSetFindFilter(?enabled '(noall symbols) ?onButtons '(noall symbols))
  comp = car(axlGetSelSet(axlSingleSelectPoint()))
  )
  refdes=comp->refdes
  println(comp->refdes)
  else
  println(refdes)
  );end if comp

;-----------------------------Net1 Selection----------------------------
if(net1 == nil then
axlSetFindFilter(?enabled '(noall nets ratsnests) ?onButtons '(noall nets ratsnests))
println("Selectionner la 1ere net (Cline ou ratsnest)")
net1 = car(axlGetSelSet(axlSingleSelectPoint()))
lpin1 = axlPinsOfNet(net1, 'pins)
num1=0
lengthnum=length(lpin1)
 while(num1
 pin=nth(num1 lpin1)
 sprintf(txt "Num: %n - Item: %s" num1 pin->parent->refdes )
 println(txt)
 if(pin->parent->refdes == refdes then
  pin1loc = (pin->xy)
  println(pin1loc)
 );end if refdes
 num1=num1+1
 );while num1
);end if net1

;-----------------------------Net2 Selection----------------------------
if(net2 == nil then
axlSetFindFilter(?enabled '(noall nets) ?onButtons '(noall nets))
println("Selectionner la 2eme net (Cline ou ratsnest)")
net2 = car(axlGetSelSet(axlSingleSelectPoint()))
lpin2 = axlPinsOfNet(net2, 'pins)
num2=0
lengthnum=length(lpin2)
 while(num2
 pin=nth(num2 lpin2)
 sprintf(txt "Num: %n - Item: %s" num2 pin->parent->refdes )
 println(txt)
 if(pin->parent->refdes == refdes then
  pin2loc = (pin->xy)
  println(pin2loc)
 );end if refdes
 num2=num2+1
 );while num2
);end if net2

;-----------------If 2 Pins Location on Component Then execute swap pins command -------------------------------
if(pin1loc || pin2loc then
sprintf(cmdstring "swap pins;pick %n %n;pick %n %n;done" nth(0 pin1loc) nth(1 pin1loc) nth(0 pin2loc) nth(1 pin2loc))
axlShell(cmdstring)
net1=nil
net2=nil
num1=nil
num2=nil
pin1loc=nil
pin2loc=nil
lpin1=nil
lpin2=nil
lengthnum=nil
pin=nil
cmdstring=nil
axlClearSelSet()
);end if 2 pinlocs

);while Finished==nil
);defun
-----END----

Many thanks in advance to those can help!
(Informations on what mistakes and bad syntax I did would be welcome!!)

   willbi.