Please see Article 9.2 of the General Conditions (Annex II of the Grant Contract):

"However, where the amendment to the Budget or Description of the Action does not affect the basic purpose of the Action and the financial impact is limited to a transfer between items within the same main budget heading including cancellation or introduction of an item, or a transfer between main budget headings involving a variation of 15% or less of the amount originally entered (or as modified by addendum) in relation to each concerned main heading for eligible costs, the Beneficiary may amend the budget and inform in writing without delay the Contracting Authority accordingly. This method may not be used to amend the headings for administrative costs or the contingency reserve."

Within the flexibility offered by Article 9.2 of the General Conditions, Annex II of the Grant Contract (see above), and in line with the limitations stipulated by it, it is possible to reallocate funds within Budget lines (Budget for the Action, Annex III of the Grant Contract).