On that Pottsville Branch site, on the maps page, the lower left map shows an all LV (bold) connection, but the lower right map shows that Pottstown to New Boston was via the PRR rails, which was the way it really was.
This site has all the old official guides where you can look at old schedules. http://www.northernfield.info/schedules.php
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If you go to 1923 for the LV, Table 16, there are trains to/from Pottsville and Catawissa, but above the train numbers at the top of the timetable is says "Pa". So I assume that means that these are actually PRR trains.
For 1922 on page 372, it also seems all trains from Delano to Pottsville are labelled "PRR".
For 1888 (the third year I tried), on page 186, it also lists Pottsville/Delano trains but WITHOUT PRR mentioned (or any train number, for that matter). So that could be one example of LV service on that stretch.
Regarding freight, I've read that PRR actually sent some coal, from Minersville for example, up the Frackville grade (over 3%!!) and then via New Boston and the LV to go north (presumably on the PRR eventually), but not for LV coal. For example, I would imagine anything from Blackwood would have run all the way back to main on the Potttsville Br.
But at least there is one example of an LV train running Pottsville to Delano.