Sibling rivalry inheritance

Hi, everyone.

My pseudo name is Kal El.  I have questions in mind I need help po.

I need legal advise po about Inheritance.
* My Parents are still alive but have Alzheimer's disease
* I have 3 siblings
* They religiously pay my parents liabilities like land taxes, ancestral house  renovations, Electricity, Water, groceries and maids and unsettled loans of my parents before they retired.
* I never contributed anything (Zero) because they say that i am the black sheep in the family.

My questions are:

1. Kapag dumating ang panahon namatay ang mga magulang namin marami silang maiiwang properties like mga bahay lupa at condominiums.  HINDI papayag na equal sharing ang mga kapatid ko sa mana dahil katwiran nila malaki ginastos nila sa mga magulang namin noon nagkasakit hanggang mamatay.
2. Gaya ng mga gastos ay ang mga Taxes, Loans, Medicines ng parents namin renovations ng properties ng parents namin etc..
3. What advise can you give me if i am the weakest link amongst the 4 siblings? i don't want sana na walang makuhang share at mahirapan makipag argue about my share sa properties na mamanahin namin.
4. Wala ako macontribute financially for some reason.
5. What are the legal remedies if they refuse equal sharing sa Mana?
6. My Parents cannot create a will and testament as they are suffering from Alzheimer's disease already.

Thank you in advance for the advise.

Kal El

hindi talaga dapat na equally ang hatian kung gumagastos sila sa pag maintain ng estates ng parents nyo. ang mangyayari dyan, babawiin muna nila yung total na nagastos nila sa mga ari arian tapos tsaka palang hahatiin equally yung matitira.

Thank you for your thought.   What does legal say about it kaya?