Answer: First, please understand that Oregon law does not directly deal with this - and neither is it addressed in most rental/lease agreements, including MHCO's. So my responses are based upon my opinion alone. Until an appellate court rules on these issues - which is unlikely, since most such cases are never appealed - the best we can do is speculate. My answers are in italics below.
1. Do we write a new lease for the remaining resident or keep the old lease with both residents on the lease? I think I would prefer to see a new lease signed by the remaining resident - even if title remains in both their names. That way, the ex-spouse cannot argue that he or she has a right of occupancy a year or two down the road, when they patch things up, or one moves out and the other moves back in. A new lease would require than any new occupants be qualified all over again. Note that if the lease is changed into the name of the remaining resident, the ex-spouse would certainly have no liability for space rent going forward.
2. Can we legally keep the resident that moved out, responsible for the lease after a divorce and separation of assets? Technically, yes. Neither the divorce decree nor the parties themselves can - without your consent - alter their joint legal duties under a lease they both signed. [This situation is not dissimilar to spouses jointly signing their mortgage and then divorcing; they both remain liable under the mortgage, even though one vacates the home.] The best a divorce court can do is to make the occupying ex-spouse primarily responsible for the rent and give indemnity rights to the non-occupying ex-spouse in case she or he end up having to pay for unpaid rent that should have been paid by the occupying ex-spouse.
3. Do we rescreen the remaining resident to see if he/she qualifies on their own? I have a visceral reaction to doing so - if they did not pass the credit requirements, then what? Deny them the right to stay in the community in which they have lived for a number of years? Kick them out without waiting to see whether they can - or will make the payments? That is like punishing the remaining ex-spouse for being divorced. Remember, the occupying ex-spouse will likely be the custodial parent, if children are involved. The non-custodial parent will likely have some child support obligation, which would then make the custodial parent's individual credit score less important. The same may be said even if there are no children; there may be a spousal support obligation by the non-occupying ex-spouse. It seems to me that it will become clear soon enough, whether the occupying ex-spouse can or will make the space rental payments, independent of what their current credit score may be.
4. If we do rescreen the remaining resident and he/she fails the credit or criminal background, what are our options? Before you re-screen, re-read my answer to Question No. 3 above. If the lease agreement or rules do not address the possibility of spouses divorcing - and I have never seen any that do - the ultimate decision on whether you may re-screen could be left up to a judge. I submit that judges do not like to evict people out of their homes unless there is a compelling reason to do so. A case in which a resident is being evicted for no reason other than that they no longer meet the credit criteria - with no evidence that they are in default under the lease or rules - would be a very difficult sell to most judges. It is unlikely that you would prevail. I compare this situation to requiring a resident to be re-screened upon a job loss or death of a spouse. In cases of such unplanned events occurring after residents have been approved, I suggest that you let the situation play itself out. If a resident cannot afford to pay the space rent, you will then have sufficient cause to evict. But to try to evict because you doubt the ability of the resident to pay rent in the future, is premature and likely to fail.
5. Who owns the security deposit or pre-paid rent? That depends upon whether you have the remaining resident sign a new lease. If a new lease is signed, you could issue a refund check to both of them under the first least, and require the remaining occupant to pay a new deposit under the new lease. It would be preferable, however, to see if they could agree to authorize you to leave the existing deposit in place, but permitting you to refund it, if appropriate, to the remaining occupant at the end of his/her tenancy. If no agreement can be reached, simply hold the deposit until expiration of the tenancy by the occupying non-spouse, and then, if a refund is in order, make the check out to both of them.