Why does the Father love the elect?

Heppe (p. 411) is normally very reliable, but this time he has me baffled. He says, citing Olevianus (De Substantia Foederis, p. 26):

The covenant of grace rested sheerly on the twofold vow which the Son in eternity had promised to the Father and on the commission which accordingly the Father had imparted to the Son; consequently only the absolute love of the Father for the Son is the cause by which the Father also loves the elect.

Does 'also' qualify 'the Father' here (as grammar would lead one to expect) or does it qualify 'the elect'? In other words, does 'the Father also loves the elect' mean here 'the Father loves the elect in addition to the Son's love of the elect' or 'the Father loves the elect in addition to his love of the Son'?

On the first interpretation it would seem that what is meant is that the Son loved the elect and the Father had no prior love for them but, since he loved the Son, loved the Son's elect, much as I might love my wife's furnishing catalogues just because she loves them rather than off my own bat? I'd always assumed, in contradiction of the above, that the Father loved the elect gratuitously, and that the Son and Spirit either loved the elect gratuitously too, or took the lead from the Father (else they might end up loving different individuals!).

On the second interpretation, is the text saying merely that the Father loves the elect only because he foresees them as 'in Christ'? In other words, is the text saying that if we had never been united with Christ the Father couldn't have loved the elect because they would never have been holy, but he can love the elect because he foresees them as being in Christ? But the problem with this line is that surely there must be a logically antecedent love that God has for the elect in order to explain why not all are elect.

Can anyone clarify this for me, please?

The 'twofold vow', according to this learned article, is explained by Olevianus thus:

The Son of God, having been appointed by God as Mediator of the covenant, becomes the guarantor on two counts: 1) He shall satisfy for the sins of all those whom the Father has given him, 2) He shall also bring it to pass that they, being planted in him, shall enjoy freedom in their consciences and from day to day be renewed in the image of God.