With nouns of the original four declension classes, these go as follows:
healmani, healmasi, healmanne, healmasse, healmō, healmē
laureni, lauresi, laurenne, lauresse, lauru, laurie
cuoroni, cuorosi, cuoronne, cuorosse, cuoruo, cuorō
talëni, talësi, talënne, talësse, talu, tali or taini, taisi, tainne, taisse
So far so good -- this is what we've had since 2005 or so. But what happens when the possessed noun is also, say, ergative?
kelve-s rāva-Ø cier-t-o-s
dog-ERG lion-ABS eat-PF-3-OBV
"The dog ate a lion"
Is fine; now what about "My dog..."? Should it be kelvesni or kelvenes or what?
kelve-ne-s rāva-Ø cier-t-o-s
dog-1SG-ERG lion-ABS eat-PF-3-OBV
"My dog ate a lion"
I think that's pretty much the way it has to go, because kelvesni is totally aesthetically unappealing, and the plural suffixes would be ridiculous: kelvesënne, etc. And I like the fact that the way I have it up there sort of resembles Turkish rather than Finnish for once.
The question, then, is what happens to the form of the possessives when case endings are added to them. -ni and -si seem pretty straightforward as -e stems; -nne and -sse must have a proto-coda for the vowel to have stayed mid, so maybe *-tnet and *-tset or something? But then, do these decline as -t stems, as per the preceding post? That would give us e.g. perhennennes, which I think is obviously inadmissible.
I think I'm going to call upon paradigmatic levelling to help me out here, and just call them stems as well, that happen to have an anomalous form in the absolutive singular for historical reasons. Let's go ahead and map out what we've got so far for all cases and numbers:
eāsi "house" with 1st- & 2nd-Person Possessive Suffixes
A eāseni, eāsesi, eāsenne, eāsesse
E eāsenes, eāsetes, eāsennes, eāsesses
I eāsenen, eāseten, eāsennen, eāsessen
P eāsenea, eāsetea, eāsennea, eāsessea
V eāsene, eāsete, eāsenne, eāsesse
eāsie "houses" with 1st- & 2nd-Person Possessive Suffixes
A eāsenie, eāsesie, eāsennie, eāsessie
E eāsenīs, eāsesīs, eāsennīs, eāsessīs
I eāsenīn, eāsesīn, eāsennīn, eāsessīn
P eāsenia, eāsesia, eāsennia, eāsessia
V eāsenē, eāsetē, eāsennē, eāsessē
Issue 1 is that I'm not at all sure I like the fact that singular and plural with possessive suffixes tends to be indicated solely by consonant length. I need to think about this; maybe I could have the plural fall into a different declension class or something? Anyway, the real problems are presented by the third-person suffixes, as we're bound to have a surfeit of vowels. I guess we should just take these one by one, tedious though it may be.
ceivasō & ceivasē "his bedroom"
A ceivasa-o > ceivasō; ceivasa + e > ceivasē
E ceivasa-o-nës > ceivasōs; ceivasa-e-nës > ceivasēs
I ceivasa-o-hën > ceivasōn; ceivasa-o-hën > ceivasēn
P ceivasa-o-da > ceivasōa > ceivasoā; ceivasa-e-da > ceivasēa > ceivaseā
V ceivasa-o-t > ceivasō; ceivasa-e-t > ceivasē
ceivasōi & ceivasēi "his bedrooms"
A ceivasa-o-i > ceivasōi; ceivasa-e-i > ceivasēi/ceivasaje
E ceivasa-o-i-nis > ceivasōis; ceivasa-e-i-nis > ceivasēis/ceivasāis
I ceivasa-o-i-hin > ceivasōin; ceivasa-e-i-hin > ceivasēin / ceivasāin
P ceivasa-o-i-da > ceivasōja; ceivasa-e-i-da > ceivasēja
V ceivasa-o-i-t > ceivasōi; ceivasa-e-i-t > ceivasēi
I need to leave the other three/five classes for later, as (1) I'm developing a pounding headache, and (2) as always I feel like these sound changes are more ad-hoc than really rigorously defined and it makes me feel like a hack. I really need to make that timeline and figure out exactly what happened when.