there is a publication called lancashire graveyards and burial sites compiled by Bill taylot and published by the lancashire family history and heraldry society that lists all known burial grounds in the county bith civic and religious and also an index as to where the registers are and if the monumental inscriptions have been recorded at the cemetary/grave yard. Most burial registers will be at the Lancashire county record office in Preston, you need to first decide what religion they were, which church they had attended, whether they would have been buried there or in the civic cemetary, which would be after about 1855 in most towns, and if so you would need to contact the local authority for info, then if you think they were buried in a churchyard and you think you have found the church, you can either check of the gravyard has been recorded and published by the LFH&HS or if the burial register is at the CRO in Preston. I can do that for you if you want though if you let me know what town you need to check,
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