To start to request from the notary. Generally require the original of this document. By the way, the whole list of documents required not only when selling the apartment, but also in its exchange, donation, etc. If you are a parent of a minor owner of the premises, then you will also need the corresponding statement about the sale of the apartment. If parents have a child there, and you're just the person who has entrusted the sale process of housing, give the child a special document certifying the absence of parents. It may be a death certificate, court decision on deprivation of parental rights or recognition of a parent missing.
Of course, you need a statement from the minor dwelling. However, only in the case when he has reached 14 years of age. In other cases, a statement from the child's guardian (if he has no parents). If you work with a certain degree of minors in the apartment, make sure to collect statements that they are not opposed to the sale, with all adult owners of the remaining shares of the dwelling.
You also grant to the guardianship birth certificate of the child and the documents confirming his right of ownership of the dwelling (deed of gift, a will, etc.). Of course, in order to sell the apartment "custody" take care of paying all the necessary bills utilities, pay the light and phone. After statements from each of them you will also need to provide the care.
Collect most of the documents in the original, but a copy of them necessarily clear. Just in case. But to put the date and his signature under his statement not in a hurry. Do it in the presence of a specialist of the guardianship. He immediately have your autograph and will endorse his signature. Remember that to hand over documents to the child must come personally to all those involved in the process. It is the child himself, his parents or guardian and those owners who do not object to the sale of a share in the apartment (if we are talking about proportion).
It is worth considering that the guardianship is easier to agree on a deal if you already have an equivalent option housing to replace the homes sold. This should take care in advance. In some cases, the guardianship gives his welcome with the wording: "with simultaneous rather than sequential sale of the apartment." This will mean that you will have to buy a new apartment, and then sell the old ones.