The stone is the least reliable document in the cemetery. It records what a family could afford at the time, in the language of the time, and it stays in place only as long as someone pays for the ground beneath it. The paper is better. Every German cemetery keeps a burial register and a plot ledger, and those two records together will tell you whether a grave still exists, who currently holds the lease, and when that lease runs out. Getting at them from the United States is mostly a matter of writing to the right office and asking a question narrow enough to answer.
Work out which office actually holds the file
German cemeteries are either municipal or confessional, and the distinction decides who you write to. A municipal cemetery is run by the Friedhofsverwaltung, usually a department of the town or the Samtgemeinde, and its correspondence address sits on the town's website under Friedhöfe. A Catholic or Lutheran churchyard is run by the parish, and the records live in the Pfarrbüro or, for older material, in the regional church archive. Small villages in Lower Saxony often have both, a churchyard closed to new burials and a communal cemetery a few streets away, and a family can be split between them.
What the register holds that the stone does not
The burial register (Sterbebuch or Beerdigungsregister, depending on the keeper) records the date of burial rather than the date of death, the section and row and plot number, the depth of the interment, and often the undertaker. The plot ledger, kept separately, records the lease: who bought the Nutzungsrecht, for how many years, when it was renewed, and by whom. That second record is the one that answers your real question. A grave can be perfectly present in the burial register and gone from the ground, because the register documents an event that happened while the ledger documents a right that expired.
Registers also carry things no monument ever showed. Reburials from another cemetery, additional interments in the same plot decades apart, a maiden name spelled the way the family used it rather than the way the mason cut it, and the note that a stone was removed and by whom. When a plot has been cleared and leveled, the ledger normally shows a date of Rückgabe or Einebnung, and the office can tell you what the ground is used for now, whether that is a new lease to another family, a lawn, or seating.
How to ask so the answer comes back complete
Write in German if you can, and if you can't, write short, plain English and expect it to be understood. Give the full name including maiden name, the date of death or a two-year window, the place of death, and your relationship to the deceased. Then ask four specific things: whether a plot is recorded, its section, row and number, the current status of the Nutzungsrecht with its expiry date, and whether a site plan can be sent as an attachment. Ask what a written extract costs and how it can be paid from abroad, since a US check is useless to them.
Offices will generally confirm by email that a grave exists, give you the plot designation, and say whether the lease is current or lapsed. Data protection rules mean the name and address of the living lease holder is usually withheld, though many offices will forward a letter from you to that person, which is the practical route back into a family that stopped writing three generations ago. The National Archives and Records Administration, which is responsible for federal records and genealogical research in the United States, follows much the same logic on living individuals, so the boundary should feel familiar.
Reading the site plan they send back
What arrives is usually a PDF of a survey drawing: a grid of numbered rectangles with a section label, an arrow for north, and one plot picked out in hatching or color. Check three things before you buy a ticket. Check that the plot number on the drawing matches the number in the email text, because transcription errors between ledger and plan are common. Check the legend for grave type, since an Urnengrab and a Wahlgrab occupy very different footprints. And check the plan's revision date, printed small in a corner, against the date of the last clearance recorded in the ledger.
Carry a printout with you. Cemetery sections in Lower Saxony are marked on cast plates at the path junctions, and the row numbering usually starts from the path, which means a plan and ten minutes of counting will put you on the exact square of ground even when nothing above it is left to read.