this is the agreement between federal government and puntland and it clearly states north Mudug belongs to Puntland.
this is the link to the report:
C- Dhismaha Dowladaha Xubnaha ka Noqonaya Federaalka: labada dhinac waxay isku afgarteen in dhismaha maamul goboleedyada lagu saleeyo sida uu dastuurku qabo, sidoo kale waxaa lagu heshiiyey in maamulka loo sameynayo gobolada dhexe ka koobnaado gobolka Galguduud iyo koonfurta gobolka Mudug, waxaa sidoo kale hoosta laga xariiqay in waqooyiga gobolka Mudug yahay qayb kamid ah Puntland.
And this is the article in the constitution that gives Puntland more powers that other states don't have:
Article 142.
Existing Federal Member States in Somalia
(1) Until such time that all the Federal Member States of Somalia are established and the adopted Federal Member State Constitutions are harmonized with the Somali Federal Constitution, the Federal Member States existing prior to the provisional adoption of this Provisional Constitution by a National Constituent Assembly shall retain and exercise powers endowed by their own State Constitution.
(2) Existing Federal Member States must be consulted in the decision-making process regarding the federal system, and security arrangements.