It would definitely not be easy.
Multiclassing into any non monk class means that you're abandoning the path of a monk for some other pursuit then later returning to it.
Abandoning means you are not still pursuing it, not matter what weapons you use or how much you say you're still training as a monk, you're not. That is what is meant by "not freely multiclassable." Since leaving a restricted multiclassing class (paladin, monk, druid) means leaving, not temporarily taking another class as a way to multiclass, any class change submission with intent to return shortly thereafter will be given much scrutiny.
The spirit of the restricted multiclassing rule is that you don't.. well, multiclass (except for with the approved classes, which there are none for monk.) The CDQ to change class exception is there for characters that leave the path for one reason or another or begin it later in life.
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Also, dwarven defender is a difficult prc as it requires a sponsor and a cause in the form of a dwarven lord, dwarven church etc. Dwarven Defenders don't just decide to become dwarven defenders, they are chosen by their sponsor.
Add that to the monk difficulty and I would call this a very difficult proposition.
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Basically, I wouldn't approve this unless you have a COMPELLING IC reason for it that develops naturally IG.