You just right click the person holding the title and then select ``buy claim''. It's right above ``request claim'' where you usually get it from the pope.
Title claim inheritance Upon succession, eligible children are given pressed claims on titles they did not inherit nor vassalise. If the parent held pressed claims themselves, unpressed claims are inherited in their stead. Unpressed claims cannot be passed down, but will revert to the former status if pressed in a war.
Click the button on the Steward which should be at the bottom and to the right of the usual buttons, then just click the desired county on the map just as you would do when fabricating a claim.
Request claim from head of faith (if you have one.) Fabricate claim sometimes will randomly grant a claim on Duchy. Claim Throne hostile scheme from Stewardship Lifestyle (Meritocracy) will give you a pressed Ducal claim against your Duke liege.
There's a little crown over the portraits of your sons, on the top right corner. Click it to designate them as heirs. You must still follow your rules of inheritance, of course (you can't designate a daughter as heir if you have a son, or not at all if you have Agnatic succession).
You CAN claim an entire country all at once. Marry a lady who has a claim to a large piece of land (say, a whole kingdom), press her claim, win, she becomes queen/duchess, the children you have with her will inherit that stuff now.
Dependency claims are made by immediate or close relatives of the deceased who have been deprived of their support and services. It is a compensation claim, not for the deceased but for their family after death.
Examples of dependent claims: a box-like metal frame, wherein the power source and the lead-gold zapper element are retained inside the box-like metal frame.
A DEPENDENCY PETITION BEGINS A JUDICIAL PROCESS, WHICH, IF THE COURT FINDS YOUR CHILD DEPENDENT, COULD RESULT IN PERMANENT LOSS OF YOUR PARENTAL RIGHTS OR IN SUBSTANTIAL RESTRICTIONS ON YOUR RIGHTS AND INTERESTS AS A PARENT SUCH AS THE ENTRY OR MODIFICATION OF A PARENTING PLAN OR RESIDENTIAL SCHEDULE OR ENTRY OF A ...
Minor children, or children of any age who are physically or mentally incapacitated from earning, get the benefit of a conclusive presumption of dependency if they were either living with the deceased employee or the decedent was legally liable for their maintenance at the time of injury resulting in death.