Removing Many-to-Many association object


I have entity with ManyValuesAssociation field like this:

  [Entity, Table('measurement', 'hr_lib')]
  TMeasurement = class(TBase)
    [ManyValuedAssociation([TAssociationProp.Lazy, TAssociationProp.Required], CascadeTypeAll, 'FMeasurement')]
    FParams: Proxy<TList<TMeasurementParam>>;

TMeasurementParam declared as this:

  [Entity, Table('measurement_param', 'hr_lib')]
  [Id('FID', TIdGenerator.IdentityOrSequence)]
  TMeasurementParam = class
    [Column('ID', [TColumnProp.Required])]
    FID: double;

    [Association([TAssociationProp.Lazy, TAssociationProp.Required], [])]
    [JoinColumn('MEASUREMENT_ID', [TColumnProp.Required, TColumnProp.NoUpdate], 'ID')]
    FMeasurement: Proxy<TMeasurement>;

    [Association([TAssociationProp.Lazy, TAssociationProp.Required], [])]
    [JoinColumn('PARAM_ID', [TColumnProp.Required], 'ID')]
    FParam: Proxy<TInvParam>;

In UI user can delete some TMeasurementParam object from TMeasurement.Params. In UI I don't call Manager.Remove, because user can press Cancel and don't commit changes.

Then user press OK, I try to execute Manager.Flush to save changes, but get exception - Aurelius try to update field TMeasurementParam.FMeasurement to nil, and execute Update in DB, but this field not null only. Then I delete object from list, I want to automaticaly delete entity from DB.
Is it possible? How? Or I always need additional flag like IsDeleted in TMeasurementParam, and call Manager.Remove(MeasurementParam) before call Manager.Flush?