Welding inside a group

How can I weld vertices by threshold inside a group node?? I am writing a code which will attach all the same named objects (this part is already solved and discussed in this forum) and then weld the vertices by desired threshold (0.001)...it is working perfectly with geometries...but when those geometries are inside a "group"...it is not taling the thresold (welding is still working though)....since the threshold is an unknown property for group node. Any solution??

My code till now:

(
fn weldverts obj =
(
$.weldThreshold = 0.001
polyop.weldVertsByThreshold obj #All
)

newworking = #()

for o in geometry do
(
if classof o == editable_poly do
(
append newworking o
)
)

i = 1

while i <= newworking.count do
(
b = newworking[i]
j = i + 1
while j<= newworking.count do
(
if (newworking[j].name == b.name) then
(
b.attach (newworking[j]) b
deleteItem newworking j
select b
weldverts b
)
else
(
j = j +1
)
)

i = i + 1
)

)