Yes it is possible to secure a rental property from abroad without being in Singapore in person. Tenancy agreements can be done electronically if both parties, mainly the tenant and the landlord are agreeable to that.
However, if there is a dispute in the matter and a legal action is contemplated, the courts will require orginal signed copies. Hence it is advisable that wet-ink signed copies to be done as soon as it is convenient preferably when Your son (if he is above 18) arrives in Singapore or You if he is not of age.
Alternatively, the contract can be sent overseas via registered postage and signed in the presence of a notary public.
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