<subject> <predicate> <object-direct> <object-indirect>.
In Idiom Neutral, dative objects are allowed to appear without the preposition to if they immediately precede direct objects. This is mostly expected when the dative is a pronoun. In terms of FS, this would yield: De volf giv de fogel en sten. Whether FS should copy this rule is an open question.
<correl.adverb> <subject> <predicate> <dir.object> <indir.object>.
<predicate> <subject> <object-direct> <object-indirect>?
vat don <subject> <object-direct> <object-indirect>?
vat/vem <predicate> <object-direct> <object-indirect>?
<subject> <predicate> vat/vem <object-indirect>?
vat/vem <subject> <predicate> <object-indirect>?
<subject> <predicate> <object-direct> <preposition> vat/vem?
<preposition> vat/vem <predicate> <subject> <object-direct>?
<correl.adverb> <predicate> <subject> <dir.object> <indir.object>?
<predicate> <object-direct> <object-indirect>!
Should FS include V2? The system described by David Parke in his Frenkisch grammar might be suitable. The advantages are familiarity and normality for all Germanic speakers except the Anglophones, but the disadvantages are extra complexity that makes FS harder and weirder for outsiders, and also the presence of ambiguity in certain places.