The benefit of the feat Share Soulmeld says
At your option, any soulmeld shaped by you and currently affecting you can also affect your familiar, animal companion, or [presumably special] mount [like a paladin's special 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. (Magic of Incarnum 41)
Does the shared soulmeld's effect include extending to the familiar, companion, or special mount essentia invested in that soulmeld by the creature's master, or does the shared soulmeld only have its basic effect, the soulmeld needing essentia invested into it by the creature with whom it's being shared? Further, does a soulmeld that's bound to a chakra extend the additional benefits for being so bound to the creature with whom the soulmeld's being shared?
For example, Jalas, an arctic snow elf incarnate 2/wizard 1 that possesses the feat Share Soulmeld, shapes at the beginning of the day the soulmeld dissolving spittle (MoI 64-5) and opts to share the soulmeld dissolving spittle with Fun, his lemming familiar. Later, on his turn Jalas takes a swift action to invest 1 point of essentia into the soulmeld dissolving spittle. If Fun is within 5 ft. of Jalas, when Fun employs the soulmeld dissolving spittle, on a successful ranged touch attack, will Fun's spittle attack deal 1d6 or 2d6 points of acid damage?
A few adventures later, Jalas, now an incarnate 3/wizard 3, has taken the feat Extra Familiar (Dragon #280 62) to become the master of another familiar, a rat. At the beginning of the day Jalas shapes then binds to his crown the soulmeld soulspark familiar (MoI 86) so that Jalas gains the service of a lesser soulspark (MoI 197-8). Jalas opts to share the soulmeld soulspark familiar with his familiars, Fun the lemming and Steamboat the rat. When his familiars are within 5 ft. of Jalas, do Fun and Steamboat each gain the service of a least soulspark familiar (MoI 197) or a lesser soulspark familiar?
Note: Assume that the DM has ruled that a soulspark familiar isn't, for the purposes of the feat Share Soulmeld, itself an actual, for-reals, wizard-style familiar, therefore preventing Jalas from bringing forth a pretty large number of least soulspark familiars by sharing the soulspark familiar soulmeld with each least soulspark familiar brought forth by the soulspark familiar soulmeld!