hi! i'm building a city in my mod (how original) but within it i want to place a quest about some stolen money. i want people to gossip about it so in the dialog i want there to be a topic called "Stolen Money" but to make it appear ingame i either have to filter it per ID or per cell. now that would consume a lot of time and would take a lot of copy paste work. now the question, how do i make a topic appear on only citizens who "live" in that city, and not to everyone in the game?

You can create a new faction, add all the NPCs in your city to that faction, and then filter the dialogue by that faction.

but what about the guards? they're already in the imperial legion.

If you used Bethesda's cell naming scheme you should require only one dialog entry for your rumor to cover every cell in your city. If a dialog entry is filtered for the cell 'Vivec', it is applied to every cell whose ID begins with 'Vivec'. Such an entry would be spoken by NPCs in 'Vivec, Hlaalu Waistworks' and 'Vivec, Guild of Fighters' as well as the exterior cells 'Vivec' and 'Vivec, Arena' - check it out yourself. I should also add that if you do want the entry used by NPCs in a particular cell within your city you can add the second filter Not Cell: Cell_ID = 1 (e.g., Not Cell: Vivec, Arena Pit).

If you have not named your cells in this nested fashion, I suggest you do if it would not be too much trouble. Otherwise you will likely encounter the inconvenience of your present design in the future.

thnx! the city in question is an underground city so there isn't one main cell. i had named the place where you come in the main hall. but because of what you just said, i decided to rename it to the general name and ditch the main hall part. too bad, it was a cool name but it saves me a lot of time so thanks!

*EDIT*
Hurrah! it worked

You don't have to have the actual named cell accessible. If I remember right, in Mournhold, the actual cell "Mournhold" doesn't have anything in it and is totally impossible to get to, they just added it for dialogue filters. All the actual Mournhold areas have some suffix (like Mournhold, Plaza Brindisi Dorom), but the actual cell still exists so it can be used.

You are correct, PK. The same applies to Solsthiem. You can't actually access that cell, but you can use it as a dialog filter to limit an NPC response to those actually somewhere in Solsthiem.