Although the standard form of the
Either/Or construct limits to choice between two alternatives, there seem to be a general acceptance to using this construct when choosing more than two alternatives, using the form
Either X, Y, Or Z. The comma before Or, is optional.
Same with the
Whether/Or construct -
Whether X, Y, Or Z ... should be acceptable.
Here is a snap of a Wiki section, on the use of
Either: (Unfortunately I cannot post a link yet) -->
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A frequent difficulty in English usage concerns the permissibility of using either to refer to more than one alternative. Generally, either refers to exactly two alternatives. When there are more, linguistic prescriptivists counsel the use of any. One generally accepted exception to this rule is when either is used as a conjunction to introduce a string of either/or alternatives:
Either she will sink, swim, or get out of the pool.
Any is not used as a conjunction, and cannot be used in this context.
As an adjective, either can mean both. For example, a driveway that is lined by palm trees "on either side" means that the driveway is lined with palm trees on both sides.
In the context of a legal contract, the term "either" can refer to several parties and/or beneficiaries. Real estate contracts often use "either" to include the buyers, sellers, and their agents.
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Hope this helps !