Setting DateTime format in Delphi with Firedac compatible with BDE Application

Question

I am migrating my application from Delphi2007 and BDE to Delphi 10.4 and Firedac. The new application is in testing, the old app is still there for backup, in case the new application fails.

So, I have 2 applications talking to the same database, one with Firedac, the other with BDE.

The following happens:

As soon as Firedac saves a DateTime field (date + time), that record can no longer be changed in the BDE application. (I use TQuery->DatasetProvide->TClientDataset, updatemode WhereAll, no persistent fields in the TQuery)

Probably, Firedac stores the time-part in a format that confuses the BDE/Datasetprovider.

Is it possible to make Firedac store time in a format the BDE does understand?

I know, the solution could be : adding persistent fields (> 100 tables), and setting the providerflag to pfInkey for all primary keys, and adding datasetproviders with updatemode "whereKeyOnly", but I do not want to change that much and spend so much time on the (very big) old (and soon to be deprecated) application that uses BDE.

I tried mappingrules in Firedac. I added 2 rules:

DateTimeStamp-> DateTime, DateTime -> DateTime.

For both rules I tested with values of PrecMax of 4,6,8. I thought maybe this way the time-value is stored with less precision, but this had no effect. Maybe some other value or mapping?

ADDITION

Editing the field with a dbExpress TSQLCOnnection instead of BDE works. The default persistent field with TQuery is TDateTime, with dbExpress: TsqlTimeStamp. It seems like the "TDateTime" field is incompattible with values stored as a timestamp. The error is raized when apllying updates. Fetching the data is no problem.