Dear Ladies and Gentlemen,

My name is Yelena, I am a Public Notary from Ukraine.
I have a friend, who needs advice in Turkish inheritance procedure.
Case details are:
Turkish Woman passed away in the present year.
She had two sons, citizens of Turkey as well.
Assuming, that no suppose, parents and any other kin present.
Woman left a testament, which orders to divide heritage to two parts – some cash on the accounts to the first son and some unmovable property – to the second one. Assuming, that shares of wealth for both them, for example are 1\4 and 3\4 for the firs and second sons accordingly.
Today I was looking at a Turkish law website discussing inheritance law and I was surprised to see regulations says about so-called «reserved portion» for children, that is 3\4 (75%) and can be shared equally between children of deceased person.
If I understood correctly from the described case and taking Turkish law into consideration, no matter what testament says, but the son, who has his share 1\4 according to testament is protected by Turkish law and has a right for 3\8 share from everything. And the second son’s share has to be decreased from 3\4 to 5\8. Is that right? Please check my conclusion.
Then my questions are:
1.If the first son, who is getting share less, than law provides him (1\4 instead of 3\8) wants to increase it and starts court – what is maximum term he can challenge testament and Public Notary resolution about providing documents for the heritage on a new owner name ?
2.In a case both sons come to agreement to settle down their shares and change testament order as they decided (equally or another way) without court – then which way they must do such agreement (for example, conclude a contract with notary formalities or just sign such contract on white paper with witnesses, or court procedure only)?
3.If no one from heirs won’t start any court procedure how long inheritance procedure lasts then?
4.How much taxes and when heirs pay from the wealth?
Thank you in advance for your reply.