在进入B底部工作表之前，您应该调用Navigator.pop
示例：

InkWell(
            onTap: () {
              showModalBottomSheet(
                  context: context,
                  builder: (context) {
                    return InkWell(
                        onTap: () {
                          Navigator.of(context).pop();
                          showModalBottomSheet(
                              context: context,
                              builder: (context) {
                                return const Text("Bottom Sheet B");
                              });
                        },
                        child: const Text("Bottom Sheet A"));
                  });
            },
            child: const Text("Home"),
          ),

您可以在关闭时简单地返回工作表A的状态。基于打开的表B。
示例：

InkWell(
                      child: Text('Press me'),
                      onTap: () async {
                        final result = await showModalBottomSheet(
                          context: context,
                          builder: (context) => InkWell(
                            child: Text('Open SHeet B'),
                            onTap: () => Navigator.pop(context, true),
                          ),
                        );
                        print(result);
                        if (mounted && result == true) {
                          showModalBottomSheet(
                            context: context,
                            builder: (context) => InkWell(
                              child: Text('CLose SHeet B'),
                              onTap: () => Navigator.pop(context, true),
                            ),
                          );
                        }
                      },
                    ),