@here4thesimz @puzzlezaddict Now this is interesting as I have somewhat of a similar problem that I have been trying to fix for months except it's not with vampires. This is the first post I have seen that comes anywhere close to what I have been experiencing. Please bear with me as I attempt to explain.
I have 3 urns that can't be deleted either because they no longer have the destroy option on them anymore and build mode will simply not let me delete them directly. I forget exactly what it says when I try in build mode My case is with ghosts who have been brought back to life by the dedeathify spell but what you are describing sounds like it could be the same issue. I think, in my case after a lot of trial and error, that there is some connection between the urn and the resurrected sim that didn't break when the sim was brought back to life so the game is seeing the urn as still attached to the sim involved.
But in your case, you created a new sim with the same name as one who died and created an urn and now the game appears to be connecting the urn to the new sim rather than the original one since it won't let you destroy the urn. I assume you have tried deleting the urn in build mode and found you couldn't. But have you? and does that urn still have the "Leave a Sugar Skull" offering on it? Urns where the ghost has been released lose that option while those that still have ghosts connected still do because you strengthened the connection. The 3 urns that have lost the destroy option still have the sugar skull option on them. Do yours?
What really caused me to get into this that my problem actually is that Grimm has stopped working at the point where the body disappears and the urn appears for all manners of death that use the original animations that have been there from base game onwards. But I have found that the new animation that came with IL where a sim dies while swimming in the swimming place in Sulani and Brichester still works and produces an urn and that urn is different from the usual one until you pick it up and place it in a sim's inventory. So my next question is have you had any problem with any other sim deaths and not producing and urn or tombstone?
So I have come to believe that I need to break the connection that I think is still there preventing me from getting rid of the urns that I presently have that I can't destroy. There are 2 ways to do this. Delete the urn or delete the sim. Doing either should break that connection. Either is what I consider a nuclear solution because of what it could do to my save.
Since I can't delete the urn by destroying it the usual way or in build mode, then the only way I see to do it is to bulldoze the lot. So in that scenario, I plan to clean out all the collectibles in the house and containers and dump them into either the family inventory or into the personal inventory of one of the sims then move the sims out into manage households. Then I'm going to save the lot to my library, bulldoze the lot and replace it with the copy from my library. That ought to break the connection. Before I move in the sims, I'm going to go back into the lot in build mode and see if I can delete the stubborn urn. If I can, then I'll move the household back in and put all the collectibles, etc. back where they were. If I can't, then I'm pretty much screwed and will probably have to abandon the save if the other way I've come up with doesn't work. That's something I really don't want to do but given no other choice, I will since I need death working.
The second scenario is to delete the sim. So what I am planning to do is to split up the household and put the affected sim into a household by herself. Then go into CAS and save the sim to my library and then simply delete that sim in manage worlds. Then I'll add the sim back from the library and use either the CAS.fulleditmode cheat or MCCC options to reset the relationships back to where they were. That should work. But I don't know.
The reason I bring this up here is that I think that @here4thesimz issue can be resolved the same way by either method. The issue is relationships and getting them back to where they were. So if @here4thesimz 's sim has only no or just a few relationships then I'd save the sim to the library and delete the sim and replace it with the library copy. If there are a lot of relationships and family members outside the active household, then deleting and replacing the lot is the best way to go especially if there are a lot of long term relationships and a big family tree.
In my case, I have two lots involved and I think I'm going to try deleting the sim on one lot since the sim, although marked as a playable, hasn't been played and the only relationships she has besides those of her household were created by other sims meeting her out in the world. In the other case, the sims involved have been played extensively and have a number of familial relationships outside the household that will make reestablishing them time consuming and maybe impossible because sims have died and there are alien pollinators involved.
So @here4thesimz , here's a solution that may work for you but since I haven't tried either yet, I don't know if either will actually work. I see no reason why they won't but just don't know for sure. I am going to try once I finish the Sugar Skulls collection in one of the households.
Hope this helps you.