Quick answer no,
What you can do however to to create your slideshow, Produce it, bring it back as a new project, then apply slow motion to it, to achieve the length you require, THEN add your music.
Robert
Intel i7 930, 16GB ram, Radeon HD 5770 1Gb,Ver. 14.12 Win7 64 bit
Intel i7 7700 HQ, 16 GB ram Nvidia GTX 1050Ti 4GB dual drives 1 TB SSD + 1 TB HDD Win 10
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