We acquired the S211s from the manufacturers directly, as part of a counter trade deal. Singapore was not involved in that transaction. Our S211s are new; some were even assembled in the Philippines.The RSAF provided the F16A/Bs to Thailand and the S211s+Helos to the PAF so I don't think they will not agree to a F5 request.
The Hueys "from Singapore" were actually from the US. Singapore simply won the contract to refurbish them -- paid for by the Philippine government.