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The presence of A/F-type {\it Kepler} hybrid stars extending across theentire $\delta$ Sct-$\gamma$ Dor instability strips and beyond remains largelyunexplained. In order to better understand these particular stars, we performeda multi-epoch spectroscopic study of 49 candidate A/F-type hybrid stars and onecool(er) hybrid object detected by the {\it Kepler} mission. We determined alower limit of 27 % for the multiplicity fraction. For six spectroscopicsystems, we also reported long-term variations of the time delays. For foursystems, the time delay variations are fully coherent with those of the radialvelocities and can be attributed to orbital motion. We aim to improve theorbital solutions for those systems with long orbital periods (order of 4-6years) among the {\it Kepler} hybrid stars. The orbits are computed based on asimultaneous modelling of the RVs obtained with high-resolution spectrographsand the photometric time delays derived from time-dependent frequency analysesof the {\it Kepler} light curves. We refined the orbital solutions of fourspectroscopic systems with A/F-type {\it Kepler} hybrid component stars: KIC4480321, 5219533, 8975515 and KIC 9775454. Simultaneous modelling of both datatypes analysed together enabled us to improve the orbital solutions, obtainmore robust and accurate information on the mass ratio, and identify thecomponent with the short-period $\delta$ Sct-type pulsations. In several cases,we were also able to derive new constraints for the minimum component masses.From a search for regular frequency patterns in the high-frequency regime ofthe Fourier transforms of each system, we found no evidence of tidal splittingamong the triple systems with close (inner) companions. However, some systemsexhibit frequency spacings which can be explained by the mechanism ofrotational splitting.

Orbital solutions derived from radial velocities and time delays for four {\it Kepler} systems with A/F-type (candidate) hybrid pulsators