Inherited Apartment Building on Land with Multiple Titles

Pardon me, 'cause here I go again with more questions.

Our case is this. We have decided to partition the estate extrajudicially. We are 4 siblings; 1 Illegitimate and 3 Legitimate.

There are only 3 properties left by our widowed mother.
1. One will be given to the illegitimate. - property with 1 TCT
2. One to the eldest legitimate. - property with 1 TCT
3. The last property will be given to the 2 other legitimate siblings. This is the one with 4 TCTs but with only one improvement which is the apartment covering all 4 titles.
Title 1 = 220 sq.m
Title 2 = 180 sq.m
Title 3 = 180 sq.m
Title 4 = 150 sq.m

Questions:
1. How do we go about partitioning this property? My concern is, even if we give 2 titles each, who will own the apartment bldg?

2. IF one sibling decides to sell his share, how is the computation for this?
I mean do we get to choose which titles to base the computation from? Or we sum the market value of all 4 titles with improvement then divide it to 2?


Thank you. And hope someone reply. I've searched this site, still hasn't come up with answers.