Im working on a kind of DAC. Im looking at the bitshares_tools library and was wondering if it can it be used with pure PoS instead of TaPOS? 

Also, my system uses some public domain external data. My idea is to have a PoS Consensus on the value of this data.

Current stake holders:
Account1:  10 coins
Account2:  4 coins
Account3:  8 coins
Account4: 3 coins
Total coins: 25

PoS Consensus:
51% of stake must sign data, data will be signed recursively. Transaction would be valid after signed by 13 coins in this example: 

Example of valid transactions: 
Account2.sign(Account1.sign(data))
Account3.sign(Account2.sign(Account4.sign(data)))

either of these transactions are valid, and once it gets into the block, the next block will then automatically generate deterministic transactions  based on the data from previous block.

The recursion would save lots of space vs traditional multi-sig.