My definition for the Kind, as I have oft pointed out, is that individuals of the same kind CAN produce offspring, not that they necessarily will in nature.
But doesn't this make "kind" the same as the biological species concept? --- "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups" (Ernst Mayr, my italics).
Your defintion seems at odds with at least one popular brand of creationism. The following is taken from AiG:
Take a hypothetical created kind A—truly a biological ‘species’ with perhaps a tremendous genetic potential. See Figure 1. (For the sake of simplicity, the diagram avoids the issue of what is meant by two of each kind aboard the Ark—however, the basic point is not affected.) Note that A may even continue as an unchanged group, as may any of the subgroups. Splitting off of daughter populations does not necessarily mean extinction of the parent population. In the case of man, the original group has not diverged sufficiently to produce new species.
Hence, D1, D2, D3, E1, E2, E3, P1, P2, Q1, Q2, Q3 and Q4 are all different species, reproductively isolated. But all the functionally efficient genetic information they contain was present in A. (They presumably carry some mutational defects as well). *
You see the dodge? By their theory of evolution-but-we-don't-call-it-that, they can have reproductively isolating speciation starting from just one kind.
Other creationist websites I've looked at seem to concur. So mere interbreeding would be a sufficient condition for two animals to be the same kind, but not a necessary condition.
So what is?
You'll notice that the author I reference does not answer that question, preferring to put up a flimsy smokescreen of lies and rhetoric.
On the other hand, the ICR seem to be leaning the other way:
"A kind may be defined as a generally interfertile group of organisms that possesses variant genes for a common set of traits but does not interbreed with other organisms under normal circumstances." (ICR Impact, "Summary of Evidence for Creation", May/June 1981)
My italics; so their definition of "kind" is more stringent than yours.
For me the solution is simple. I would place creatures of obvious phenotypic similarity into the same Kind ...
But there are lots of obvious phenotypic similarities. Mammals, for example, all have obvious phenotypic similarities, that's what makes us group them together as mammals. At what point would you like to start ignoring the similarities (and, apart from being a creationist, why)?
This would allow for the diversity created by simple speciation, without requiring the problematic increase in genetic complexity which, as we all know, has never been observed or documented.
Polymer-metabolising microbes not withstanding, of course.
If you wish to be wrong about this, start a new thread or revive an old one where it's on topic.