Although the preamble specifically recommends Chambers, unless I'm wrong the "new member" is not in it, though it is in Collins. Also, I think it would have been better if it had said that the transfers would together form a new member, rather than each spelling one. To me that implies a new member each time.
I'm about 95% done. 36a (normal clue) suggests to me the answer LEK or even LAK but neither doesn't seem to fit the definition.
For 18d I have the letters ?NEI?? but no suitable word goes there as far as I can see so I must be wrong somewhere.