I have a legacy database. I want to Import data in a new table A and compare it with an existing table B.

I created new entities and UpdateDatabase created them in the database. This works ok.

However, Updatedatabase throws Errors, because it tries to  (but does not) delete all other existing tables, for which no entities exist. Unfortunately FK relations are dropped. 

I tried to overcome this by using modelnames, but this seems not to  be what I need. 

How can I exclude existing tables from schema Validation?

Aurelius doesn't remove foreign keys if the table is not mapped. 

It doesn't try to delete existing tables.
It also doesn't  "throw" errors. It just silently report errors in the Errors property. You can simply ignore them.
You should not need to do anything.
Sorry for beeing not precise.

[22.01.2020 20:15:08][Trace][Value: Invalid database structure. 90 Errors, 0 Warnings, 0 Actions][Type: string]
[22.01.2020 20:15:08][Trace][Value: Error: Table: dbo.KATALLERGEN - Removed.][Type: string]
[22.01.2020 20:15:08][Trace][Value: Error: Table: dbo.KATARTIKELGRUPPE - Removed.][Type: string]
[22.01.2020 20:15:08][Trace][Value: Error: Table: dbo.KATAUSWERTUNGSGRUPPE - Removed.][Type: string]
[22.01.2020 20:15:08][Trace][Value: Error: Table: dbo.KATBEREICH - Removed.][Type: string]
[22.01.2020 20:15:08][Trace][Value: Error: Table: dbo.KATDIAETEIGNUNG - Removed.][Type: string]

This is what I called "throws errors". Tx for clarifying, that these are no errors. Maybe another wording would be helpful?

You are explicitly logging such data from the TDatabaseManager information?

Well, it's named Actions, Warnings and Errors for the user to understand what's happening and what's missing. More information here:

I see, tx. However, my question still is: Any chance to have existing tables to be ignored?

They are ignored, that's what the report says, it's ignoring tables, thus reporting them.

I really appreciate your feedback and Aurelius is such a great product! I love it.

Having that said, maybe I am allowed to request a slighter less alarming wording. I know what this means, but given some customers admin who looks at the logs, they will cause some irritation. So, no problem on my side, it is just looking ahead and trying to avoid trouble.

Again: Thanks for your ongoing support!

But it's you that is logging those. Just filter the logging - simply check the words and do not log such messages, or change the text at your own will.