I'm not a solicitor but as far as I know solicitors have to enquire as to the source of funds and satisfy Anti-Money-Laundering legislation. But your sources all sound perfectly legitimate so you've nothing to fear there.
At present you can receive a gift of up to €33,500 from your brother and €250,000 from your mother without any Gift Tax liabilities. But you've just reduced your allowances by taking these gifts. So the €15,000 you're receiving from each of them would be counted in calculating possible taxation of any future gifts or inheritances from them.