1.
In the case of aggravation of an invalidity for which a person is receiving benefits under the legislation of one or more Member States, the following provisions shall apply, taking the aggravation into account:
(a)
the benefits shall be provided in accordance with Chapter 5, applied mutatis mutandis;
(b)
however, where the person concerned has been subject to two or more type A legislations and since receiving benefit has not been subject to the legislation of another Member State, the benefit shall be provided in accordance with Article 44(2).
2. If the total amount of the benefit or benefits payable under paragraph 1 is lower than the amount of the benefit which the person concerned was receiving at the expense of the institution previously competent for payment, that institution shall pay him/her a supplement equal to the difference between the two amounts.
3. If the person concerned is not entitled to benefits at the expense of an institution of another Member State, the competent institution of the Member State previously competent shall provide the benefits in accordance with the legislation it applies, taking into account the aggravation and, where appropriate, Article 45.