If there is no will there are no such priority heirs. The only one exception is a disabled person (disabled, or retired, or minor) who has been dependent from the decedent not less than one year before his death. He/she could be one of the 7 degrees heirs. In his case it is not important whether this heir resided with the decedent or not. Such an heir inherits jointly with the other heirs.
If a disabled person (disabled, or retired, or minor) who is not one of the 7 degrees heirs has been dependent from the decedent not less than one year before his death and resided together with the decedent such a person also may inherit. This heir inherits jointly with the other heirs. If there are no other heirs such disabled heir inherits as an heir of the 8th degree.
If you make a will you also may have heirs of compulsory share (for example, minor or disabled children, disabled spouse or parents). If at the time of death you have such heirs they may inherit even if the will was made not to their own advantage.