The feat Share Soulmeld (Magic of Incarnum 41) has as the following as its benefit:
At your option, any soulmeld shaped by you and currently affecting you can also affect your familiar, animal companion, or mount. The creature in question must remain within 5 feet of you to receive the benefit. If the creature leaves this radius of effect, it loses the benefits of the soulmeld until such time as it returns within 5 feet.
Perhaps—as is my wont—I'm overreading, but this benefit seems awfully vague. I've previously asked if a creature sharing a soulmeld benefits from its master having bound that soulmeld and invested essentia into that soulmeld here, so there's no need to rehash that, but now the PC actually has the feat Share Soulmeld, a familiar—a mink named Stinky—, and enough essentia and soulmelds for the feat Share Soulmeld to create problems next session. On to the issues:
When does the meldshaper exercise the option? It seems unlikely that the meldshaper must exercise this option when the soulmeld's initially shaped, for example, since a meldshaper needn't ever unshape soulmelds. Further, once the meldshaper picks a soulmeld to share, how can that picked soulmeld be changed? Can it be changed? (Note that the feat does not contain a Special entry allowing it to be taken multiple times!)
The phrase and currently affecting you raises some flags. Does this mean, for example, the soulmeld dissolving spittle (64-5) can't be shared because the soulmeld doesn't technically affect the meldshaper and, instead, grants the meldshaper an attack? Is a shared soulmeld limited to soulmelds that provide skill bonuses and the like that only affect the meldshaper?
A strict reading of the rules is a fine way to address the above, but answers stemming from the feat's use in play—what decisions were made about how to use it, how those decisions affected play, and if that experience was worthwhile—are also cool. Jalas the incarnate/wizard wants to use this feat to its fullest, yet its benefit seems to leave a lot to the imagination.
To be clear, there's no errata for Magic of Incarnum, and no sample character possesses the feat Share Soulmeld for comparison.