With some notable exceptions (try getting a Frau at any Lufthansa lounge to bend the rules), I find allowances can be made in almost any situation if you run into the right person. My wife and I (flying in F) got our three kids (flying in C), into the Concorde Lounge in Heathrow by being extremely nice. It will certainly not always work, but a smile can go a long way, particularly when the lounges aren't jammed.