Good day.
To obtain a state-style death certificate, if you are a relative of the deceased, you must apply to a court outside the temporarily occupied territory of Ukraine and submit an application together with documents confirming the fact of death (in your case, this is the Certificate of Death from a military unit).
> According to Article 317 of the Civil Procedure Code of Ukraine, an application to establish the fact of the death of a person in the temporarily occupied territory of Ukraine may be filed by relatives of the deceased or their representatives to a court outside such territory of Ukraine.
If you are not a relative of the deceased, then you should contact the relatives of the deceased or their representatives and, together with them, submit an application to the court outside the temporarily occupied territory of Ukraine in order to obtain a state-style death certificate. As mentioned above, various documents can be submitted to confirm the fact of death, including a death certificate issued by the command of a military unit.
There are grounds for which you may not be subject to conscription for military service during mobilization. Among them are:
reserved for the period of mobilization and wartime by state authorities, other state bodies, local self-government bodies, as well as by enterprises, institutions and organizations in accordance with the procedure established by the Cabinet of Ministers of Ukraine;
recognized in accordance with the conclusion of the military medical commission as temporarily unfit for military service due to their health for a period of up to six months (with subsequent passing of the military medical commission);
men who are dependent on three or more children under the age of 18 (such men can be called up for military service if they agree only at their place of residence);
men who independently raise a child (children) under the age of 18 (such persons can be called up for military service if they agree and only at their place of residence);
men dependent on a disabled child of subgroup A under the age of 18;
women and men who are dependent on an adult child who is a disabled person of the I or II group until the child reaches the age of 23;
adoptive parents, guardians, custodians, adoptive parents, foster parents, who are dependent on orphans or children deprived of parental care, under the age of 18 (such persons can be called up for military service with their consent and only at their place of residence );
engaged in constant care for persons who need it, in accordance with the legislation of Ukraine, in the absence of other persons who can provide such care;
In all other cases, you may be subject to administrative or criminal liability for failure to appear at the police station.
It is also worth considering that the delivery of a summons does not mean that you will immediately serve or go to the combat zone. Summonses are issued both for clarifying military registration data and for passing a military medical commission.
If such a condition is specified in the contract (or in the company's internal documents) that payments are not made without submitting a medical report on death, then the actions of the insurance company are legitimate. You can provide them with a medical certificate of death - this will be the confirmation.
Also, the insurance company can independently submit a request to the medical institution regarding the occurrence of an insured event regarding the insured person, that is, your father.