This is an interesting question about style.
According to Strunk and White, the final full stop should be omitted unless the sentence is "wholly detached", which I take to mean that the sentence does not occur within another.
Parentheses. A sentence containing an expression in parenthesis is punctuated, outside of the marks of parenthesis, exactly as if the expression in parenthesis were absent. The expression within is punctuated as if it stood by itself, except that the final stop is omitted unless it is a question mark or an exclamation point.
- I went to his house yesterday (my third attempt to see him), but he had left town.
He declares (and why should we doubt his good faith?) that he is now certain of success.
(When a wholly detached expression or sentence is parenthesized, the final stop
comes before the last mark of parenthesis.)
- page 18, Strunk and White, The Elements of Style
However, those examples are not complete sentences, except for the last, where the sentence inside begins with a capital letter and ends with a full stop.
Grammar Girl, a contemporary authority on such matters, states this more explicitly.
For the most part, these two rules seem fairly easy to understand—complete sentence: terminal punctuation inside; partial sentence: terminal punctuation outside. However, when you have a sentence that contains another complete sentence within parentheses, the punctuation could become confusing. Let’s say you want to add the complete sentence “I can’t believe it!” inside parentheses within another complete sentence. In this case, the exclamation point would go inside the closing parenthesis and then a period would go outside: “I ate the whole box of donuts (I can’t believe it!).”
- Bonnie Mills, read by Mignon Fogarty, Grammar Girl, "Parentheses, Brackets, and Braces", QuickAndDirtyTips.com
This gets us a single sentence. The Punctuation Guide extends this explicitly to multiple sentences, though no full example is given.
Parentheses (always used in pairs) allow a writer to provide additional information. The parenthetical material might be a single word, a fragment, or multiple complete sentences.
When a parenthetical sentence stands on its own, the closing punctuation mark for the sentence is placed inside the closing parenthesis.
- The idea that theoretical physics can be taught without reference to complex mathematics is patently absurd. (But don’t tell that to the publishers of such mathematics-free books—or the people who buy them.)
- Parentheses - The Punctuation Guide
Supposing (but not agreeing) that there can be two separate sentences in succession in a sentence, should each of those sentences take a capital letter at the beginning and a full stop at the end? If yes, why is the full stop at the end of the second such separate sentence missing (despite the second such separate sentence taking a capital letter at the beginning)?
Secondly, if there could be two separate sentences in a sentence, then there could be even three, four, five and so on. What is the limit? How many separate sentences could be there in a sentence?
Finally, is the placement of the separate sentences in the sentence correct? Can a separate sentence be placed anywhere in the sentence? Or, should such placement meet some rule or logic?
To your first question, the quotes above suggest that there is some flexibility regarding the terminating full stop. Given the specifics, I would lean towards including rather than excluding it.
To your second question, you may have as many sentences within a set of parenthesis as you wish.
To your final question, there is no restriction about where your parentheses should be located within the enclosing sentence. Naturally, the parenthetical portion should go within the parentheses.
Nevertheless, as we are discussing matters of style, one should strive for clarity. Parenthetical statements are intended to add information, but only as an aside. The main sentence should still be primary. The womb, as you delightfully term it, becomes distended if the parenthetical statements dominate the parent sentence. One should then consider whether its contents should be allowed independent existence, as it were.
In the case of your sample sentence, the main sentence is still primary. However, if you wished to reword it to avoid multiple sentences in a single set of parentheses, you can consider the following:
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