Hi!
I was creating a block that is bigger than 1x1x1 with a custom tile entity.
When i place the block, a part of the struct is spawned around (for now 1 single block above) and the tile entity is copied in the other position of the struct, but it result to be null.

Here is the code:

The Central Block:

public class ColossalChest extends BaseChestBlock {

    protected static final int SIZE = 5;

    public ColossalChest() {
        super(Block.Properties.of(Material.METAL), BaseChestTileEntityType.COLOSSAL_CHEST::get);
    }

    @Override
    public void playerWillDestroy(World world, BlockPos pos, BlockState state, PlayerEntity player) {
        super.playerWillDestroy(world, pos, state, player);
        destroyStructure(world, pos);
    }

    private static final BlockState AIR = Blocks.AIR.defaultBlockState();

    private void destroyStructure(World world, BlockPos pos) {
        final BlockState STRUCT_BLOCK = com.ike.tenchest.Blocks.COLOSSAL_CHEST_PART.get().defaultBlockState();
        world.setBlockAndUpdate(pos, AIR);
        world.setBlockEntity(pos, null);
        BlockPos above = pos.above();
        if (world.getBlockState(above).equals(STRUCT_BLOCK))
            destroyStructure(world, above);
        BlockPos west = pos.west();
        if (world.getBlockState(west).equals(STRUCT_BLOCK))
            destroyStructure(world, west);
        BlockPos east = pos.east();
        if (world.getBlockState(east).equals(STRUCT_BLOCK))
            destroyStructure(world, east);
        BlockPos south = pos.south();
        if (world.getBlockState(south).equals(STRUCT_BLOCK))
            destroyStructure(world, south);
        BlockPos north = pos.north();
        if (world.getBlockState(north).equals(STRUCT_BLOCK))
            destroyStructure(world, north);
        BlockPos below = pos.below();
        if (world.getBlockState(below).equals(STRUCT_BLOCK))
            destroyStructure(world, below);
    }

    @Override
    public void setPlacedBy(World world, BlockPos pos, BlockState state, @Nullable LivingEntity entity, ItemStack stack) {
        if (entity instanceof PlayerEntity) {
            placeStructure(world, pos);
        }
        super.setPlacedBy(world, pos, state, entity, stack);
    }

    private void placeStructure(World world, BlockPos center) {
        final BlockState STRUCT_BLOCK = com.ike.tenchest.Blocks.COLOSSAL_CHEST_PART.get().defaultBlockState();
        TileEntity blockEntity = world.getBlockEntity(center);
        System.out.println(blockEntity);
        BlockPos above = center.above();
        world.setBlockAndUpdate(above, STRUCT_BLOCK);
        world.setBlockEntity(above, blockEntity);
    }

    @Override
    public boolean hasTileEntity(BlockState state) {
        return true;
    }

    @Nullable
    @Override
    public TileEntity createTileEntity(BlockState state, IBlockReader world) {
        return new ColossalChestTileEntity();
    }
}

And the Block of the struct: 

public class ColossalChestPart extends Block {

    public ColossalChestPart() {
        super(AbstractBlock.Properties.of(Material.BARRIER).strength(-1.0F, 3600000.8F).noDrops().noOcclusion());
    }

    @Override
    public ActionResultType use(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand, BlockRayTraceResult rayTrace) {
        if (world.isClientSide) {
            return ActionResultType.SUCCESS;
        } else {
            INamedContainerProvider inamedcontainerprovider = this.getMenuProvider(state, world, pos);
            System.out.println(inamedcontainerprovider);
            if (inamedcontainerprovider != null) {
                player.openMenu(inamedcontainerprovider);
                player.awardStat(Stats.CUSTOM.get(Stats.OPEN_CHEST));
                PiglinTasks.angerNearbyPiglins(player, true);
            }
            return ActionResultType.CONSUME;
        }
    }

    @Nullable
    @Override
    public INamedContainerProvider getMenuProvider(BlockState state, World world, BlockPos pos) {
        TileEntity entity = world.getBlockEntity(pos);
        System.out.println(entity);
        return entity instanceof INamedContainerProvider ? (INamedContainerProvider) entity : null;
    }

    public boolean propagatesSkylightDown(BlockState p_200123_1_, IBlockReader p_200123_2_, BlockPos p_200123_3_) {
        return true;
    }

    public BlockRenderType getRenderShape(BlockState p_149645_1_) {
        return BlockRenderType.INVISIBLE;
    }

    @OnlyIn(Dist.CLIENT)
    public float getShadeBrightness(BlockState p_220080_1_, IBlockReader p_220080_2_, BlockPos p_220080_3_) {
        return 1.0F;
    }
}

In the getMenuProvider function of the ColossalChestPart the TileEntity result to be Null.

How can I make multiple blocks interact with a single main TileEntity?
Maybe I could create a TileEntity for the ColossalChestPart to which I pass the main TileEntity?