Synonyms include flawless or ideal.
To recover something, or to retrieve it.
An adjective meaning free from error could be flawless or perfect.
Something that is lost and then found is recovered.
The adjective is indivisible.
The word could be innovator, or in one sense a visionary.
Invisible
Something very old could be primeval (earliest, first) or primordial (oldest).
The adverb could be freely or voluntarily.
There is no one-word substitute in English for "son-in-law."
The word you want is florist.
Substitute goods are goods that can serve as replacements for one another; when the price of one increases, demand for the other increases. One may substitute tea for coffee. A perfect substitute is an identical product. One may substitute a Ford for a Toyota.
The term is exorbitant. Something with a high price is called expensive.