The phrase "and so allow" is correct and usable in written English.
It can be used to indicate that one action or condition enables or permits another action or condition to occur.
Example: "The new policy is designed to streamline our processes and so allow for greater efficiency in our operations."
Alternatives: "thus permit" or "thereby enable".
The "probationers" will expand the numbers of carers performing these tasks and so allow more time for them.
Some members of the opposition suspected that the system was bound to fail and so allow the incumbent president, Gloria Macapagal Arroyo, to cling to power.
By the same token, they provide oil producers with more predictable future revenues, and so allow them to expand more confidently and borrow more cheaply.
It is one of the marvels of evolution that they are able to do this, and so allow the development of multicellular creatures.
Mr Museveni has already amended the country's 10-year-old constitution to abolish presidential term limits and so allow him to run again.
The core inflation rate was invented in the 1970s as a way to exclude the impact of temporary food and oil supply shocks, and so allow the Fed to focus on the underlying trend.
Apparently, King Ghāzī was also disenchanted with the group in power and so allowed the government to resign.
Tragedy, he reckoned, generates pity and fear, and so allows the healthy purging of those same emotions.
In computer simulations he lets them evolve "genetically", and so allows them to adapt and fit models of real-world financial markets.
And cancelling the planned plants might benefit TXU, by leaving Texas short of power and so allowing the firm to raise prices.
The advantage of NMR spectroscopy is that it works with molecules in solution, and so allows maps to be made of proteins that will not crystallise.
